Keith is an antagonist in ALF. He is an animal shelter worker that captures ALF in an alley using a rope over his neck. He believes that ALF is a dog. When a grumpy girl coming to buy a pet came, she told Keith, "What is that monstrosity?" when she saw ALF.
The girl then got a cat, and asked what Keith's name was. The girl decided not to name the cat Keith, and when ALF kept making noises by tapping a pan, Keith opened ALF's gate, which allowed the alien to run away and take the cat (who the girl named Damien).
Keith is an actor that works part-time at the animal shelter. When he learns that the girl's father is a producer he says that he was in a commercial with one of the cats in the shelter where he did the voice, saying, "Oh boy! Salmon chips! They're purr-fect!" He also invites the producer to a workshop production of Extremities where he is the one in the fireplace. (The information in this final paragraph is only found in the uncut version of the episode).