Gary Dean Richrath was an American guitarist, best known as the lead guitarist and a songwriter for the band REO Speedwagon from 1970 until 1989.

REO Speedwagon, or simply REO, is an American rock band from Champaign, Illinois. Formed in 1967, the band cultivated a following during the 1970s and achieved significant commercial success throughout the 1980s. Their best-selling album, Hi Infidelity (1980), contained four US Top 40 hits and sold more than 10 million copies.