"It Pays to be a Singing Doorknob"

This article reveals that voice actor Jim Cummings -- who does everything from deep-voiced movie-trailer narration to legit singing to a truly uncanny Sterling Holloway impression -- is one of the top 10 box-office stars in the world based on the amount of money grossed by movies he's participated in.

The late Paul Frees was another voice actor with a big box-office track record; he's best known as Boris Badenov on Rocky and Bullwinkle, but because he was so great at deep announcer voices (including a renowned Orson Welles impression), he can often be heard on the soundtracks of movies that needed some deep-voiced narration, like The Manchurian Candidate and The Carpetbaggers. Frees would also be brought in to dub other actors; he reportedly dubbed Tony Curtis's Josephine voice in Some Like It Hot, and in Louis Jourdan's first scene in Gigi, all the people he talks to are voiced by Frees.