Girl Genius
Girl Genius

A Horrible Rat is a construct created by Doctor Francisia Monahan. And she didn't create just one but an enormous horde of them. They are found on Big Rat Island, where Monahan has her secret laboratory. It seems likely that she created these rats for the first time on the Island, since the creation process involves the use of contaminated water from the Queen's Wellspring on the Island, which possesses Dyne-like mutating properties. There are also normal, wild rats on the Island, which may be the source of the specimens used in Monahan's Island lab research program.


The resulting Rats are huge (as big as a bear), strong, fast, and deadly; with an extremely venomous bite. They can also shrug off a great deal of punishment. They can be killed by destroying the brain or decapitation, but cumulative damage from lesser injuries seems to have little effect. Another of their horrible traits is a foul odor, which has been compared to rotting wet socks.[3] The resemblance to Jägers in both method of creation and subsequent behavior has been noted in-strip.

They do display a fear of cats, if they can be conned into believing said cats are big enough.

Beyond serving as a very effective way for Monahan to guard her lab and keep unwelcome visitors off of Big Rat Island, they are among her test-subjects when it comes to probing the powers of the aforementioned water.

When Monahan ascends to Queenhood, she is able change the Rats' size, and give them wings. She tries to give one of these "improved" specimens to Agatha as payment for a perceived debt, but Agatha is able to beg off.

Monahan's love of rats[]

Dr. Monahan is completely obsessed with rats, to a degree that seems extreme even for a Spark.

List of Monahan's Rats[]

While only one of Dr. Monahan's rats has been referred to by name in the comic, it seems likely that the good doctor has names for all her specimens/precious pets.

  • Weginald

The Works[]

Three cards from the original 2001 version of "The Works" game: Doctor Monahan, Dr

Doctor Monahan, her rats, and her Diabolical Rat-Stretching Engine.

Creatures similar to, although not identical with, the Horrible Rats are shown on a card in the original 2001 version of The Works: Dr. Monahan’s Rats. There are two copies of this card, with the details Mad, Giant, and Pests. The creatures on this card are much bigger that the Horrible Rats as portrayed in the comic, about twice as large. They also look more "cartoony" and less like real rats.

On her card, Dr. Monahan is shown holding a terrified-looking normal-sized rat in one hand and a hypodermic syringe in the other. This may lend some credence to the idea that the Horrible Rats are constructs created from normal ones. (Her card has the details Mad, Villain, and Spark.)

The final rat-themed card in The Works is Dr. Monahan’s Diabolical Rat Stretching Engine. This mechanism hasn't been seen in the comic to date and it is not clear that it ever will be. However, it does explain how the rats got so big. (This card has the detail Machine. Uniquely, it isn't worth any points itself, but increases the value of Pest cards for one turn.)

Possibly relevant outside information[]

Doctor Monahan was named after the Foglios' real life friend, bridesmaid, Rat stretcher, [4] and business associate Carol Monahan. It is not known how Carol feels about this honor.

Sherlock Holmes Reference[]

In "The Adventure Of The Sussex Vampire" Sherlock Holmes makes an indirect reference to an unpublished adventure, which he refers to as "the case of the ship Matilda Briggs and the Giant Rat of Sumatra", which is "a story for which the world is not yet prepared". Given the nearly universal popularity of the Sherlock Holmes series, a connection seems quite likely.


  1. Ariadne Steelgarter: "I hate those horrible rats!" , last panel, page (008), volume 21.
  2. Last panel, page (017), volume 22.
  3. After Violetta compares an odor on the island to rotting wet socks (panel 5), Krosp adds that the odor also smells like rats with something really wrong with them (panel 7). Furthermore, the Professoressa mentions (in her comments posted below that page) that while the pet rats she has owned haven't smelled like wet socks, "these are terrible abomination-of-science rats". Zeetha, when she apprehends him, says that Thomas Crothers smells like "all the wet socks," and Crothers himself says he is trying to smell like them .
  4. Because the Foglios were taking a real vacation on the occasion of their 25th wedding anniversary, Kaja posted a copy of their wedding program to the Girl Genius comic website. On it, Carol Monahan is described as (among other things) the publisher of Rat: the Magazine for the Spontaneous Generation. On the Girl Genius Patreon page, in the entry (subscription required to view) for comic page posted on Monday, May 31, 2021, Kaja states, "Doctor Monahan started out as a joking reference to our friend Carol Monahan, who draws little cartoon rats of the most charming type."