Aislín McGuckin (born May 1974) is a Northern Irish actress. She has appeared in theatre, television, and film roles. Her early film work includes The Nephew and The White Countess. From 2014 to 2015, she starred as Letitia MacKenzie in the Starz series Outlander, and in 2020, played Marianne's mother, Denise, in the BBC One miniseries Normal People.