Maren double-dipped on McDonald's commercials. Not only did he play the Hamburglar, he also played Mayor McCheese! Since his face is covered, it's really hard to tell if these two commercials are his. Either way, they're hella fun to watch.
He also played a moleman in Superman and the Mole Men. This is a clip from it, but if you'd like to laugh hysterically at how they made superhero movies in 1951, watch the longer one below.
And for nostalgia, here's his scene in Oz. Maren's the one in the middle.