Mark Otis Selby (born in Enid, Oklahoma) is an American blues rock singer-songwriter, guitarist, multi-instrumentalist and producer. He is a solo artist, signed to ZYX Records in Europe, and one half of performing duo with his wife, songwriter Tia Sillers. He also plays guitar in recording sessions for musical artists such as Kenny Rogers, Johnny Reid, Keni Thomas, Jimmy Hall and Wynonna Judd.

Selby is perhaps best known for the number of songs that he co-wrote with the blues-rock artist Kenny Wayne Shepherd which includes the number one single "Blue on Black". This song was also Billboard Magazine rock track of the year in 1998. Selby also collaborated with Sillers on the number one song "There's Your Trouble" which was recorded by the Dixie Chicks and won the band their first Grammy Award for Best Country Performance by a Duo or Group with Vocal in 1999.