In a series of sketches on Sesame Street, Baby Bear brings Hero Guy to life by drawing a picture of him and singing his theme song. These sketches first aired in Season 32, and appeared on occasions until Season 38. When Hero Guy, who is also a bear, springs to life as an animated character, he and Baby Bear embark on adventures together. Although they often face unexpected challenges, Hero Guy never fails to save the day.
Hero Guy's voice is nearly identical to Baby Bear's, which is perhaps to be expected given his status as Baby Bear's creation.
Baby Bear gets Hero Guy to turn into a cow to act out the rhyme "Hey Diddle Diddle", but Hero Guy keeps turning into other animals, such as a pig, a rooster, a hippo, and a lion. He finally morphs to a cow, but likes being the Hippo, so Baby Bear changes the nursery rhyme.