Peter McDonald (born 28 January 1972 in Dublin) is an Irish stage and screen actor. He grew up in Mount Merrion in South County Dublin. His mother, Brenda Costigan is a cookery writer and his father, Richard McDonald sells bailer twine. He is related to Leigh McDonald of Australia. He was educated at St Michael's College on Ailesbury Road in Dublin and graduated from University College Dublin with a Bachelor of Arts, English and a Master of Fine Arts, English in 1994.

He got his start in theatre while at University. He was part of UCD's very active Drama Society and was a member of Fly by night theatre company.