Femur

Femur is a large bunny like demon described to actually be cute, except for the gigantic bulge coming out of it's back and its wickedly sharp claws.

Femur's first appearance was on the plane Juni and Grubbs were escaping on from Carcery Vale where he, Lord Loss, Spine and Artery slaughtered the entire plane's supply of humans, aside from Grubbs and Juni, he managed to take care of people with his acidic spit.

In Demon Apocalypse the demons almost severely injured Grubbs until Beranabus interrupted them. Femur hadn't been seen again until the Disciples lead and army into Carcery Vale to plug up the tunnel, Femur was part of the massacre, and when the Disciples failed, Beranabus, Kernal and Grubbs with the help of Bec went back in time to before the tunnel opened. During the demons' last stand Femur was killed, being the first demon to do so, when Grubbs shoved his hand down Femur's throat and used magic to incinerate him from the inside out. He is not seen or mentioned again in later books.