The Four Tops [often billed by Motown as 'Four Tops'] are an American vocal quartet, whose repertoire has included doo-wop, jazz, soul music, R&B, disco, adult contemporary, and showtunes. Among a number of groups who helped define the Motown Sound of the 1960s, including The Miracles, The Marvelettes, Martha and the Vandellas, The Temptations, and The Supremes, the Four Tops were notable for having Stubbs, a baritone, as their lead singer; most groups of the time were fronted by a tenor. The group was the main male vocal group for the songwriting and production team of Holland-Dozier-Holland, who crafted a stream of hit singles, including two Billboard Hot 100 number-one hits: "I Can't Help Myself (Sugar Pie Honey Bunch)" and "Reach Out I'll Be There".