William Emanuel Cobham Jr. (born May 16, 1944) is a Panamanian–American jazz drummer who came to prominence in the late 1960s and early 1970s with trumpeter Miles Davis and then with the Mahavishnu Orchestra. According to AllMusic, Cobham is generally acclaimed as fusion's greatest drummer.

He was inducted into the Modern Drummer Hall of Fame in 1987 and the Classic Drummer Hall of Fame in 2013. AllMusic biographer Steve Huey said, "Generally acclaimed as fusion's greatest drummer, Billy Cobham's explosive technique powered some of the genre's most important early recordings – including groundbreaking efforts by Miles Davis and the Mahavishnu Orchestra – before he became an accomplished bandleader in his own right. At his best, Cobham harnessed his amazing dexterity into thundering, high-octane hybrids of jazz complexity and rock & roll aggression."

Cobham's influence stretched far beyond jazz, including on progressive rock contemporaries like Bill Bruford of King Crimson and Danny Carey of Tool. Prince played a version of Cobham's Stratus in concert. Phil Collins, who named Mahavishnu Orchestra's The Inner Mounting Flame as a key influence on his early style said, "Billy Cobham played some of the finest drumming I've ever heard on that record."