Loona

Loona is one of the main villain protagonists of "Helluva Boss", a spin-off series set in the same universe as Hazbin Hotel.

History
Loona is a large, anti-social hellhound with wolf-like features - she primarily acts as the secretary of I.M.P but is infamous for being extremely bad at her job due to deliberate lack of care or respect for anyone or anything around herself.

Loona is encouraged in her behavior by Blitzo, who babies her and sees her as a daughter - a fact that infuriates Moxxie, she in turn loves to torment Moxxie (a trait she shares with her adoptive father).

Loona does not actively engage in mass murder on Earth like the other members of I.M.P but is still very much as evil as you may expect - prone to random rage she has been shown as fully willing to severely injure or even kill infants (such as when she ran out into the street and randomly kicked a passing baby into the sky just to "let off steam").

Trivia

 * just like the imps (Blitzo, Moxxie and Millie) it is likely that Loona is an actual native of Hell rather than a sinner (such as most of the cast of Hazbin Hotel), which would make her a true demon.
 * Loona despises other creatures but has shown very small signs of actually caring for Blitzo, since she vaguely smiled when he called her family and somewhat defended him against Moxxie near the end of the pilot.
 * Loona's outfit depicts the inverted pentagram, which is one of the most recognized symbols of Satanism (a similar pentagram is also seen in the very sky of Hell in Hazbin Hotel and seems to be how Hell itself is divided into sections).