Barbara Callcott (née Farrell, c. 1947 – 10 May 2013) was an Irish-born Australian television personality, best known for her portrayal of the schoolteacher "Mrs Marsh" in a series of Colgate toothpaste advertisements that ran from 1976–1991.

After the long-running television and print commercials began in the 1970s, she became an Australian pop culture icon. Although the series ended in 1991, she continued intermittently in the campaign until shortly before her death. She continued to support the education of Australian children on the benefits of good oral health habits off-screen as well as publicly.