Killer is a slender tan Schnoodle with slender legs and a brief potbelly. He wears a black spiked collar and a pair of spectacles.
Killer is really cowardly, pusillanimous, frightened, and nervous, and for each of his failures, Carface tries to have him killed but he manages to convince him not to each time. He is also his messenger, he stays out of the action in the final battle and escapes from the hideout, after Charlie sacrifices himself saving Anne Marie. Killer makes sure she makes it to shore and reunites her with her newly adoptive parents. However, despite his cowardice, he can be slightly rebarbative and gruesome, wanting to squeeze Charlie's head between a pair of pliers as well as owning a ray gun, despite not knowing how to use it.
He is not seen in the sequel, but he returns for the TV series as Carface's partner in crime. In the series, Carface doesn't abuse him as much as he did in the first movie and never tries to kill him.
In the series' finale, we see how Killer celebrates Christmas. It is shown in the musical number "I Always Get Emotional at Christmas Time" that he has a wife and son, but neither relative is ever mentioned by name, nor do they ever speak. In fact, they only make a cameo appearance.
After finding out that Charlie Barkin is back, Killer informs this to Carface, and is later seen in the shadows plotting Charlie's death with Carface's other minions. He assist Carface in Charlie's death by getting him (and himself) drunk at the Mardi Gras, blindfolds the drunken Charlie and helps his boss run him over with a car and off the docks. Not too much later, he and Carface are forcing Anne-Marie into talking to a nearby rat, declining her access outside, until Charlie gets her out. Much later, Carface is about to feed Killer to some piranhas, when the Schnoodle told his boss about a ray gun, to which Carface agrees. The next day, Carface and Killer attempt to shoot Charlie and Anne-Marie, but Killer misfires, causing the pit bull to shout, "Morons! I'm surrounded by morons!" Well into the climax, Carface keeps telling Killer to shut up, as if he doesn't need him anymore, and Carface fights Charlie on his own. The last Killer is seen in the movie, is when he pushes Anne-Marie away from the sinking boat and then leaves the scene, reformed while Anne-Marie is rescued by authorities and then brought to Kate and Harold's house who adopted her along with Itchy, Flo and her puppies and cured her illness. It remained unknown what happened to him after this.
Killer isn't seen or mentioned once in the second movie, as Carface is the lackey to Red instead.
In All Dogs Go to Heaven: The Series
Killer reappears in the series, once again serving as Carface's bumbling minion. However, in one episode, Sidekicked, Carface is absent, leaving Killer to have a turn to be the main villain, as a day in the limelight.
In the beginning Killer just followed along with Carface and did what Carface told him to do. But at the end gives a true heart. Killer is in the Christmas spirit and so is Carface.