Bob is a main protagonist of the stop motion animation segment Prometheus and Bob, seen on the Nickelodeon animated sketch comedy series KaBlam!. He is a caveman that gets educated on how to live in modern society by Prometheus, an alien. Bob used to be full of hair but now has none due to a laser incident in the first tape Prometheus recorded of him (the last Prometheus and Bob segment aired, "Tape 1").
Bob is usually depicted as being scared by Prometheus's lessons due to them either being too vague to make full sense for him (watching television, celebrating a birthday, and doing laundry being examples) or Prometheus's way of teaching being too forceful for a slow learner like him. The Monkey often interrupting the teaching with pranks doesn't help, either.
Despite this, Bob is usually an optimist and he can understand Prometheus's knowledge well (like learning how to use a spear) if left alone.
Trivia
In "Tape 677: Evolution Chamber" when Bob got evolved into his modern form, he resembles Prometheus in his appearance (sans his skin color), hinting at being related to Prometheus's species.