A former child actor who entered the entertainment industry in the early 1990s, Spencer Klein first appeared on the big screen at age five, with a minor role in the film "I Don't Buy Kisses Anymore", a Jason Alexander-lead romantic comedy. Following that 1992 effort, Klein guested on the family drama series "Life Goes On" the next year. 1993 also found the actor co-starring in all 11 episodes of the short-lived ABC sitcom "Joe's Life", in which Klein portrayed the main character's youngest son. Klein continued to work in television, showing up on a 1994 episode of the classic TV comedy "Seinfeld" and the entire first (and only) season of the 1995-96 drama series "Live Shot", which chronicled the daily lives of a Los Angeles news team. Klein also began acting in films again around this time, receiving roles in the 1996 Christmas flick "Jingle All The Way" (starring Arnold Schwarzenegger), and the 1998 movies "Slappy and the Stinkers" and "Free Enterprise". Then, in 1999, Klein became the voice behind the title character in the popular animated Nickelodeon series "Hey Arnold!" The third actor to portray the character, Klein played the role until the series ended in 2004. He also served as Arnold's voice in the 2002 feature film "Hey Arnold! The Movie".