Who is the only voice actor to have a speaking part in all of the Disney Pixar feature films?

The answer is John Ratzenberger because he has the distinction of having a speaking part in every Disney Pixar feature film. Ratzenberger is known for voicing various characters in the Pixar films, including Hamm in the "Toy Story" franchise, P.T. Flea in "A Bug's Life," and Mack in the "Cars" series, among others. His presence in all Pixar films has become somewhat of a tradition, and he is often referred to as Pixar's "good luck charm."