Zeuxippe is a young woman who in the Girl Genius side-story Maxim Buys A Hat. She is the strong willed granddaughter of Ol' Man Death the sandwich-maker, who rode with the Jagers and Never. Lost. A. Fight. And the princess who took him away from all that. Well, presumably; at one point OMD says that Zeuxippe came to be there thanks to "mysterious processes". He's probably just being sarcastic and/or discreet, but with this comic you never know.
She is one of the people in the comic with a star on her face.
She works as a waitress in OMD's sandwich shop in a small town near Mechanicsburg, and doesn't really believe the stories about her grandfather's Jager days until Maxim shows up to make his three official attempts at claiming OMD's fabled hat. She quickly shows that whatever their actual biological relationship, she's inherited something from her grandfather: she cows him into spilling his Jager story by threatening him with an expensive schlongnwurst, and then beans Maxim with a large glass jar of sandwich-fixings when the Jager momentarily gets the upper hand in the fight. This of course only arouses Maxim's interest, and he offers to take her for a ride. (On his horse! It's a nice horse!) OMD unsurprisingly cuts off this line of thought by attempting to boot Maxim out of the shop, but then it turns out Maxim actually has a trick up his sleeve.
It may be that Zeuxippe is attracted to Maxim in return. In the last panel , Maxim is walking away in triumph from Ol' Man Death's shop having non-violently acquired the hat, and in his hand is a note, reading Call me, and signed with the letter Z, probably Zeuxippe. We haven't seen her again in the official comic, but a fan was inspired by this possibility to make her one of the stars in the non-canon Jaegermonstern Dating Guide comic.
Possibly relevant outside information
The name also appears several times in Greek mythology.
'ZEUXIPPE' (Zevtfinr-n). 1. A sister of Pa-sithea or Praxithea, was a Naiad and married to Pandion, by whom she became the mother of Procne, Philomela, Erechtheus and Butes. Who they are in Grecian mythology is long and complicated.