- "So I stopped it. And I did it my way this time. No more negotiating. No more promises. No more second chances. And I did it alone. Because I had to. And it worked."
When we first join our story, Baron Klaus Wulfenbach is the reluctant tyrant  of much of Europa. While he functions as the primary antagonist throughout much of the First Journey and has been Agatha's foil, his character is quite complex.
Publicly at least, his only surviving family members are his very talented adult son, Gilgamesh, and a mysteriously absent wife, about whom he is quite closemouthed. The Baron himself is a construct. The rules of succession of the Fifty Families may therefore make him ineligible to inherit or retain his title... but he's ruling anyway. The circumstances leading to Klaus's reassembly have not been revealed in the comic to date, but it has been indicated in outside sources that the late Baron and Baroness Wulfenbach (re)created their heir from (parts of) their three sons.
The Baron is one of the most powerful Sparks of his generation. He would much prefer to be off exercising his gift by studying the nature of the Spark instead of engaging in politics, but he sees it as his duty to maintain the Pax Transylvania because he's the only one who can. However, his methods are different from those his best friends, Bill and Barry Heterodyne, used to establish peace prior to their disappearance. While the Heterodynes aimed for more mutually cooperative politics based on diplomacy and second chances, Klaus has had far less patience for those who show themselves to be hostile or uncooperative. He maintains this "overgrown kindergarten situation" with a stern and exasperated hand. Accordingly, the Baron's core policy for keeping peace and order in his empire can be summarized as "Don't make me come over there."
In earlier years, he studied with Dr. Tarsus Beetle at Transylvania Polygnostic University. He joined with the Heterodyne Boys and their constructs, Punch and Judy, for adventures — killing monsters, stopping out-of-control Sparks — and generally bringing an end to the chaos running rampant over the land which was ruining the lives of peasants and merchants defenseless against (e.g.) giant carnivorous pea-plants. Roughly forty years before the start of the story, he visited England for a time and supposedly had some sort of Doomed Tragic Romance with that country's immortal queen Albia.
Later, he also started an affair with Lucrezia Mongfish, the Beautiful Daughter of one of their opponents, the evil Dr. Mongfish. Although he likely knew she had romantic interest in Bill Heterodyne, he was shocked at Lucrezia's announcement of her acceptance of Bill's marriage proposal. Vowing to stop her from ruining his best friend's life, he found instead that she had drugged him and was about to ship him off to parts unknown. Again, the comic itself is yet to say where those parts were, but thanks to external info supplied by the Foglios (see below), it's pretty much an open secret that his destination was Skifander — for four years.
He apparently accepted his fate and settled down in the "Lost" City as much as someone like him ever could. The Professors have "leaked" a confirmation, mostly via book preorder bookplate sketches, that Klaus was known as "Chump" while he was in Skifander, and therefore is Zeetha's and husband of Queen Zantabraxus. The comic itself has shown a single-panel which indicates that he eventually staged an urgent escape from Skifander with an infant via one of the Queen's Mirrors. Arriving at the other end, wherever that was, he was by two Dreen, who informed him they would be assisting with his empire, in exchange for an unnamed action on Klaus's part.
The Other showed up a little over three years after Klaus's disappearance. Some time after this, the Baron reappeared in Europa (again with a baby boy in tow) only to find that all the work he had done with the now-vanished Heterodyne Boys had been undone, and things were even worse than before.
His family lands were ravaged during the aftermath of the Other War and his ancestral castle destroyed. He built a massive airship which in effect served as his new "castle", a slow-moving floating city in itself, reasonably named the Castle Wulfenbach. His "conquest" of Europa is simply the side effect of the only declaration he has ever made; "Don't Make Me Come Over There" - that any entity that attacked his barony would be met with swift and overwhelming force, and the aggressor's lands and property would be forfeit. Through the enforcement of this policy, his "barony" expanded until he maintained an iron-fisted peace over large chunks of eastern Europa.
When Klaus first returned from hiatus, people flocked to him, only too happy to take him up on his offer of protection. However, as time went on, and the Baron had to make increasingly difficult decisions, his popularity waned. People began to whisper rumors that he had been The Other, or speculated that he was responsible for the disappearance of the Heterodyne Boys.
By the time the story began, Klaus has become a controversial figure; some believe his rule is what is best for Europa and serve him wholeheartedly, others grudgingly accept that he's better than any of the current alternatives, and a few brave (or foolish) souls plot his downfall for one reason or another. Popular entertainments mock him as a coward—yet the public does not seem to notice not only the discrepancy, but the fact that he lets these defamations persist unedited.
In general, whatever faults Klaus Wulfenbach may have, what we have seen of the other Sparks of Europa powerful enough to challenge him argues in favor of the belief that he is far preferable as ruler to any alternative. His son and heir, Gilgamesh Wulfenbach, while as ruthless as his father, appears the value of his father's methods.
And then there's Agatha.
Klaus and Agatha
Klaus first meets Agatha when she is a student at Transylvania Polygnostic University. Due to the effects of the locket she has been wearing, she is held in general contempt by most of the students and faculty there who are acquainted with her, and this colors Klaus' initial impression of her. In the course of one eventful day, Agatha's locket is stolen and her protector Dr. Beetle dies.
When Agatha subsequently breaks through, constructing her first clank, she does so in her sleep, and does not herself realize that she is the one who had constructed it. Neither does Klaus, who assumes, when he captures both her and Moloch von Zinzer, that Moloch is the Spark who built it, and that he is her "spark boyfriend trying to get revenge of Dr. Beetle's death". He thus takes them both back to Castle Wulfenbach, though not with any great sense of urgency.
Klaus finally learns who Agatha really is at the same time as Agatha herself learns it, when he encounters her with her adoptive parents Adam and Lilith Clay — actually Punch and Judy. As this is the occasion of her escape from Castle Wulfenbach, his opportunity to make use of this knowledge is limited. He confiscates the locket from Von Zinzer and banishes the man to Castle Heterodyne.
He also sends Captain Bangladesh DuPree and his son Gilgamesh to retrieve Agatha (none of that romantic nonsense, got it?), but the duo are deceived by Master Payne's Circus using the burnt body of a circus member who has been killed by a rogue clank. Klaus reconstitutes the body and thus finds out about the deception, but far too late to locate the circus again. Or so it would seem, as he almost simultaneously receives word about a fatal "lab accident" in the city of Sturmhalten....
Even under the best of circumstances, Klaus regards a new Heterodyne heir wandering about Europa as a grave menace to the peace which he has managed to establish. Given attempts by House Valois to establish a false Heterodyne heir as part of their attempt to conquer Europa, he isn't far wrong.
The circumstances, however, immediately deteriorate from the best to the worst. Klaus proceeds in force to Sturmhalten, whereupon he confronts Agatha, who has had Lucrezia's personality superimposed on her brain. And she has with her a miniature hive engine containing a single very special wasp that can enslave a Spark, with which she makes Klaus a revenant. Ironically, this encounter also has the result of freeing Agatha from Lucrezia's control, as Klaus has Agatha's (repaired) locket on his person, and Lucrezia/Agatha puts it on, thinking it to be nothing more than a trinket. This does not prevent a battle between Klaus and Agatha, in which Lars loses his life saving Agatha's, and in which Klaus is seriously injured by a flying circus wagon falling on him.
He is taken to the Great Hospital at Mechanicsburg and placed under the treatment of his old mentor Doctor Sun where he immediately becomes the target of numerous assassination attempts. He is at least allowed one moment of undiluted happiness and pride when he witnesses Gil taking down an invading force of battle-clanks.
Klaus unsurprisingly proves to be a difficult patient, and is finally placed in forced sleep to regenerate his injuries. In the process of his treatment, he also comes under the control of the copy of Lucrezia which has been installed into Anevka Sturmvoraus's clank body, though the extent of that control is never made entirely clear; at the very least, he is able to pass a subtle warning of his fate (and his belief that death would be his only escape and the only hope for peace) to his son via an unwitting courier -- and right under The Other's metallic nose.
Then, during the Siege of Mechanicsburg, the Great Hospital is destroyed while he is still a patient there. Captain Vole claims that he is dead, but to no one's real surprise, Klaus quickly reappears alive (and apparently fully-healed) on Castle Wulfenbach - possibly due to "Princess Anevka", though she is not with him, and is not seen again until the strip's action moves to England, long after.. well, keep reading.
Klaus's first act upon reappearance is to round up his son and anyone who has talked to his son since Gil returned to Castle Wulfenbach-- and then to test Gil with a Wasp eater. The weasel acts as if Gil is a revenant, but there are severe doubts as to whether or not this is an accurate pronouncement. Klaus also begins gathering his forces for a massive attack on Mechanicsburg and Castle Heterodyne, but it is quickly and universally noted that he is behaving in a very atypical (ie, disorganized and inefficient) fashion, leading to the popular theory that he is deliberately sabotaging whatever orders he has been given by clank-Lucrezia. (To offer one example, when the Vespiary Squad flees Castle Wulfenbach, he sends after them his rather inappropriately equipped Stealth Fighters, and saddles the pursuers with restrictive rules of engagement.) Nevertheless, following the arrival on the scene of The Real Knights of Jove and the reveal of the true amount of the forces he has (rather chaotically) gathered to assault the city, Klaus is able to convince Gil to submit to a procedure wherein a copy of Klaus's personality is imprinted on Gil, in a similar fashion as Lucrezia was forced on Agatha. (Though by its own later admission, this copy is not as complete or sophisticated as what is stuck in Agatha.)
Gil is then dispatched to personally collect or kill Agatha, a failed effort which ends with Gil being expelled from the city by Franz the dragon. Following Agatha's full reactivation of the Castle Heterodyne, the rest of Klaus's forces are also repelled. Klaus's reaction to this setback is to collect the Take-Five Bomb from his vaults, drop into the city and set it off in person, creating a bubble of frozen time around himself, Agatha/The Other (or such was the plan) and the city, leaving his "controlled" son "safely" in charge of the Empire.
Two and half in-story years later, the failure of this plan is on display: his empire has mostly collapsed, Gil is slowly unraveling mentally, Agatha is still free, and the use of the Take-Five has attracted the unwelcome attention of a Hideous Extradimensional Being: Type 1. (Eventually Agatha and Tarvek are able to extract the Klaus-copy from Gil's mind, but the other problems continue to fester.)
Every spark has a recognizable, somewhat hereditary style. Klaus's spark is more abstract than most: He has the gift of analysis and synthesis, which allows him to identify Sparks simply from their creations, and on a more pragmatic level, allows him to match up personnel with their most appropriate and fulfilling job functions. His preferred application of his ability is the study of the Spark itself, which he does, in part, through brain coring. However, his comments to Othar indicate that he would prefer to simply provide a Spark with the tools they need and observe them over a long period of time. But Othar, being who he is, is far too dangerous to give resources and was moved straight to destructive testing. We have at least one example of his intention to sponsor a spark. He has also shown interest in the work of the Sparky children/hostages he fosters and at least one student was sent to live aboard Castle Wulfenbach simply for the experience.
His Spark allows him to study the technology of others, which he then adapts and improves for his own use. This often means the end result is "bigger and better" than the original concept. (Castle Wulfenbach is an excellent example.) His 'bigger and better' tendencies with other people's inventions tends to allow them to be weaponized as well, if that wasn't their purpose in the first place. (Fire-fighting equipment able to freeze objects solid and make materials brittle.)
As a man of science and education, the Baron not only maintains his studies, but occasionally contributes to the body of literature in the areas of his specialties. According to his son, the Baron wrote a monograph on how to communicate in the workplace. It was received with a great amount of... excitement.
Like all Sparks, Klaus has his "amusing quirks," such as a love of waffles and a tendency to infect himself and his son with every disease and poison he can find as proof against assassination attempts. Seeing as they are still alive, this may actually be a good idea. He claims at one point that every woman with the Spark that he has ever known has tried to kill him; whether this is a result of his spark or a more fundamental personality issue is left to the reader.
- Main article: Klaus-in-Gil
Klaus makes a deal with his son Gilgamesh where the latter allows him to install a "personality overlay" which has the effect of preventing damage to the Empire or to Gil himself, with Agatha seen as the primary threat. Everyone agrees that Klaus's personality overlay is "not really him", but it is distressingly similar to what Lucrezia does nonetheless.
The print novel Agatha H. and the Voice of the Castle features a scene where Zeetha shares with Gil a couple more details of "Chump's" time in Skifander: he never told his wife much about his background, beyond the fact that he came from a place called "Europa", and he ran away from the city when Zeetha was only a month old. One reason she came to Europa is that she is looking for him, although it is left ambiguous if this a personal quest, or part of her official mission.
During an online interview, the Foglios revealed that Skifander has a bias against twins, strongly implying that saving Gil's life was the reason for Klaus's departure. (Even in the print novel, it's again not made clear if Zeetha's family has ever given her a reason for Chump's leaving, or if before meeting Gil she even knew she had a brother.)
Klaus Wulfenbach is a card in The Works. The details are Construct, Villain, and Spark.
Relevant outside information
Near the start of chapter 6 the novel Northanger Abbey by Jane Austen is a list of novels. One title on the list is Castle of Wolfenbach. The name was noted, changed slightly, and used as the last name for the Baron, from the initial draft name of "Ujebeck". The novel The Castle of Wolfenbach was written by Eliza Parsons and published in 1793. The Wolfenbach in the story is a Count, not a lowly Baron.
In the early drafts of the Girl Genius story, the Baron was supposed to die in the first story arc. 
For those unfamiliar with nobility rankings in Europe, a baron is the lowest rank, and a baron's fief is typically about as much land as one can see from the top of their castle. It's possible that is what gave Klaus the idea to use a patrolling high-altitude airship as his "castle", as one can see just about all of Europa from the top of Castle Wulfenbach (if not all at once). However, given how Barons are supposed to answer to higher nobility like Counts, it's doubtful that Europan nobility is impressed. Intimidated, possibly, but not impressed. Not that Klaus cares.