Duncan Stewart is a fictional character from the Australian soap opera Home and Away. He made his first appearance during the episode broadcast on 14 June 1989. He was initially portrayed by Allana Ellis, with actor Lewis Devaney taking over the role from 1990 to 1998. Brendan McKensy assumed the role in 1998 until Duncan's departure in 2001. McKensy later reprised the role in 2004 and 2005 and made his last appearance on 13 July 2005. The character was reintroduced on 19 July 2016, with Benedict Wall cast in the role. Duncan is the son of Ailsa and Alf Stewart. His 2016 reappearance marked the first time in 27 years that he, Alf and his half-sister Roo Stewart had been on-screen together. During his time in Summer Bay, Duncan befriends Tori Morgan, becoming a love rival for Nate Cooper.

Ailsa Stewart is a fictional character from the Australian television soap opera Home and Away, played by Judy Nunn. She made her first appearance during the episode broadcast on 17 January 1988. Ailsa was married to Alf Stewart and had a son Duncan. When Nunn decided to leave to devote more time with her novels, she was one of only four original cast members. The role of Ailsa was briefly played by theatre star Nancye Hayes whilst Nunn was taking leave due to illness in 2000.