Osvaldo, el Gruñón (Oswald the Grouch) is Oscar the Grouch's Puerto Rican counterpart. He first appeared in the Season 11 premiere of Sesame Street, voiced by Norberto Kerner and puppeteered by Richard Hunt.
- The Sesame Street Dictionary (1980)
- The Sesame Street Word Book (1983)
- Ernie's Finish the Picture (1985) (as "Oswaldo")
- Splish-Splashy Day (1989)
- What's in Oscar's Trash Can? and Other Good-Night Stories (1991) (as "Uncle Oswaldo")
- Oscar's Grouch Jamboree (1994)