Chester Anton Mathias Hansen is a Canadian musician and songwriter, best known as bassist of instrumental group BADBADNOTGOOD. As a Grammy Award-winning songwriter, Hansen often works with his bandmates and producer Frank Dukes and is credited for co-writing hit songs by Drake, Kendrick Lamar, Daniel Caesar, and Kali Uchis, among others.

Sour Soul is a collaborative studio album from Canadian jazz instrumental hip hop band BadBadNotGood and Wu-Tang Clan member Ghostface Killah. It was released worldwide on February 24, 2015.