He is best known for his appearances on the Broadway stage, which include Lyman in Barnum, The Rum Tum Tugger in Cats, Inspector Javert in Les Misérables, The Beast in Beauty and the Beast, Chauvelin in The Scarlet Pimpernel, Frank N. Furter in The Rocky Horror Show, Charlemagne in Pippin, Mal Beineke in The Addams Family, Charles Frohman / Captain James Hook in Finding Neverland, The Man in the Yellow Suit in Tuck Everlasting, and Meyer Wolfsheim in The Great Gatsby.
His film credits include the Critters series, A Chorus Line, Big Top Pee-wee, and Solarbabies.
In an interview with the Hartford Courant, Mann said: "When I was doing the junior class play — it was called 'In Deadly Earnest' — at the end of a scene, the script said, 'They kiss.'
For $35 a week, he was offered the job of performing in the annual outdoor theater spectacular The Lost Colony, during summers on the Outer banks of Manteo, North Carolina.
[4] He made his true break-through performance in the original Broadway cast of Andrew Lloyd Webber's Cats in 1982, in which he met and starred alongside his future wife, Charlotte d'Amboise.
Mann played "Old Tom" in Paul Green's outdoor drama The Lost Colony in North Carolina, and later returned to his theatrical roots to direct the show for 2 seasons.
[15] He then appeared in the world premiere of The Studio written and directed by his brother-in-law Christopher d'Amboise, at South Coast Repertory, Costa Mesa, California in March 2006.
In November 2009, he originated the role of Mal Beineke opposite Nathan Lane and Bebe Neuwirth in the Chicago tryout of a musical adaptation of The Addams Family.
[20] In 2015, he took over the role of Charles Frohman/Captain James Hook in the Broadway musical Finding Neverland, replacing Anthony Warlow, who left the show on September 27.
[23] And he gave a “commanding” performance starring as Edgar Degas in the West Coast premiere of Marie, Dancing Still at Seattle's 5th Avenue Theatre in 2019.