Stephen Lee "Steve" Viksten (July 19, 1960 - June 23, 2014) was the voice actor of Oskar Kokoshka, Caesar, and others, and a writer of the show. He wrote the most stories for the show out of all writers, with 65 stories, plus the movie. He also co-developed the show with creator Craig Bartlett and writer Joe Ansolabehere.
Viksten was born in Ventura, California on July 19, 1960. His father was the vice president of the local Sears. During his teenage years, Viksten's family moved to Arcadia, California, where Viksten became editor of Arcadia High School's newspaper. After graduating from Arcadia High School in 1978, Viksten attended several universities including the University of Missouri, UCLA, and Cal State Fullerton, though he did not obtain a bachelor's degree.
In addition to Hey Arnold, Viksten wrote multiple episodes of Rugrats, Recess, Duckman, and The Simpsons. Viksten's sole contribution to the latter, season 22's "Homer Scissorhands," was his final writing credit before his death. He died of a heart attack on June 23, 2014 at the age of 53. He was given a posthumous tribute in the end credits of Hey Arnold! The Jungle Movie along with cast member Vincent Schiavelli and Nickelodeon archivist Kevin Iwaki.
In every episode of Seasons 1-4, Steve is credited as Co-Producer. In Season 5, (including Hey Arnold! The Movie), he's credited as Co-Executive Producer instead. Steve is not credited at all in "April Fool's Day" and "The Journal", meaning he did not participate in the production of those episodes.