Marcellus Rodríguez-López is an American multi-instrumentalist musician and younger brother of Omar Rodríguez-López. He is best known as the keyboardist and percussionist of The Mars Volta and the drummer for Zechs Marquise. He also produces electronic music under the moniker Eureka the Butcher and has performed with De Facto since 2024.

Omar Alfredo Rodríguez-López is a Puerto Rican guitarist and songwriter. He has formed or played in several bands, including The Mars Volta, At the Drive-In, Antemasque, and Bosnian Rainbows. He was the bassist for the dub band De Facto. He has embarked on a solo career, both in studio and in concert, frequently described as experimental, avant-garde, or progressive. He has also collaborated with numerous artists, such as Damo Suzuki, John Frusciante, El-P, Mon Laferte and Calle 13.