|Introduced in||"Her Parents"|
|Latest appearance||"Lady Rainicorn of the Crystal Dimension"|
|Voiced by||Henry Rollins|
He has a short body, is horizontally-striped with rainbow colors, almost bald, and wears glasses due to poor vision. It is unknown if male Rainicorns have shorter bodies than females, or if he is just a short Rainicorn. The fact that Ethel is long and Bob is short may be the reason that Lady has a medium length. Also, he chooses to use the universal translator device, unlike his daughter, which means he speaks Korean like his daughter and wife. Unlike Lady and his wife, his head is blue instead of pale pink. Unlike his daughter, he and his wife both have eyes that are two dots and not the big, cartoon eyes that belong to most characters.
- According to Lady Rainicorn, a dog saved his life during the Rainicorn-Dog Wars.
- Bob and Ethel Rainicorn live at 47 Rainbow Street.
- His hair is a pale blond; however, in the photo of the dog who saved Bob's life, his hair is the same color as his skin.
- Bob is credited as "Rainicorn Dad" in the end credits for "Her Parents," as opposed to his real name. Ethel, however, is credited by her proper name.
- Though speaking Korean, his mouth movements match what the translator is saying.
- In the picture of Bob and the dog, Bob's hands are a light blue, but when Bob and Ethel visit, Bob's hands are green.