Bryan Kei Mantia, known professionally as Brain, is an American rock drummer. He has played with bands such as Primus, Guns N' Roses, Praxis, and Godflesh, and with other performers such as Tom Waits, Serj Tankian, Bill Laswell, Bootsy Collins, and Buckethead. He has also done session work for numerous artists and bands.

Primus is an American rock band formed in El Sobrante, California in 1984. The band is currently composed of bassist/vocalist Les Claypool, guitarist Larry "Ler" LaLonde, and drummer Tim "Herb" Alexander. Primus originally formed in 1984 with Claypool and guitarist Todd Huth, later joined by drummer Jay Lane, though the latter two had departed the band by the beginning of 1989, and were replaced by LaLonde and Alexander respectively.