He is best known for his role in the films Goin' South, Fuzz, The Last Starfighter, Weird Science, The Great Outdoors, Baby Boom, and Silent Night, Deadly Night. Leach has also made guest appearances in television shows such as The Brady Bunch, The Partridge Family, Bonanza, Tales from the Crypt and many others. During the fall of 1976, he was cast in the role of Mickey "Wig" Wiggins, an airplane mechanic, in the six-episode CBS adventure series, Spencer's Pilots, starring Gene Evans, Christopher Stone, and Todd Susman.