Muldoon became widely known for playing Austin Reed on Days of Our Lives, a role that made him a familiar face to daytime drama audiences. He also appeared on Melrose Place, where he showed a darker side through the character Richard Hart.
His film career included the cult science-fiction movie Starship Troopers, where he played Zander Barcalow. Over the years, he also appeared in shows like Who’s the Boss? and Saved by the Bell, along with later film projects.
Beyond acting, Muldoon worked as a producer and remained active in the industry through new projects. He is remembered for his versatility, consistency, and the lasting impression he made across decades of entertainment.