Actor - Character (number of episodes)

Samantha Smith - Mary Winchester (37)
Ruth Connell - Rowena MacLeod (33)
Kim Rhodes - Sheriff Jody Mills (19)
Lisa Berry - Billie/Death (15)
Genevieve Padalecki - Ruby (13)
Emily Swallow - Amara (12)
Felicia Day - Charlie Bradbury (12)
Cindy Sampson - Lisa Braeden (11)
Rachel Miner - Meg Masters (10)