Young Man Rivers is Old Man Rivers' son and a minor character in Foster's Home for Imaginary Friends. He only appeared in the Season 4 episode called "Neighbor Pains". He bears a similar resemblance to Lucas from Mother 3 and Earthbound, also Flapjack from The Marvelous Misadventures of Flapjack. He is voiced by Grey DeLisle/Grey Griffin. His only line is "Tag, you're it". He is deceased near the end of the episode.
- His birthdate is 5/15/2002.
- He has a similar resemblance to Lucas from Mother 3/Earthbound and Flapjack from The Marvelous Misadventures of Flapjack.
- His final appearance was in "Goodbye to Bloo" in the goodbye ceremony scene with Old Man Rivers, his grandfather.
- He made funny faces to Mac and Bloo, and Mac and Bloo make funny faces at him back.
- He loves to play with toys, including his tricycle, his red ball and his blocks. He doesn't like it when Mac, Bloo, Wilt and Madame Foster throw papers at his grandfather's lawn when he's sitting on it along with the purple flowers on the right of him.