Big Old Bullfrog is a frog who lives at the Otter Pond in Bear in the Big Blue House. Big Old Bullfrog appears in the song "Hello Doctor" from "That Healing Feeling." He calls Doc Hogg because he has a stomachache from eating too many flies. He is also seen in "What's the Story?" and is also seen in the opening of "A Berry Bear Christmas." He is sometimes referred to as simply "Bullfrog."

The puppet used for this character had first appeared in episode 204 of The Animal Show as Bufo the Toad.