In 1991, The Ren & Stimpy Show was one of Nickelodeon's original three Nicktoons series along with Doug and which other show?
Ren and Stimpy (characters): Ren and Stimpy, created by John Kricfalusi, are the title characters in the American-Canadian animated television series "The Ren & Stimpy Show". The Ren &amp; Stimpy Show:  It premiered on August 11, 1991 as one of the original three Nicktoons, along with "Rugrats" and "Doug".
Rugrats