He was a close friend of the late Jim Varney, who voiced Slinky in Toy Story and Toy Story 2. When Toy Story 3 went into production, Pixar came to Clark to take up the role of Slinky, which he later reprised in Toy Story 4.
He made appearances in both the series finale for both Home Improvement (1991-1999) and Boy Meets World (1993-2000).