Rebecca "Bex" Mack is a character in the Disney Channel television show Andi Mack. She is portrayed by Lilan Bowden.

Bex is the free-spirited daughter of the Mack family. After a long absence, she returns home on her younger sister Andi's 13th birthday to get her life back in order.

She later reveals to Andi that she is not her sister, but her mother.