Leonard is a three-time Tony Award nominee, winning Best Featured Actor in a Play in 2001 for his role as A. E. Housman in Tom Stoppard's "The Invention of Love". He had a prior association with Stoppard's work, playing the role of Valentine in the New York premiere of "Arcadia" at Lincoln Center in 1995. His 2003 Tony nomination was for his portrayal of Edmund Tyrone in a well-received revival of Eugene O'Neill's "Long Day's Journey Into Night" that co-starred Philip Seymour Hoffman, Brian Dennehy and Vanessa Redgrave. Leonard has also appeared in Broadway musical productions, in 2001 replacing Craig Bierko as the lead performer in a revival of "The Music Man". On February 8, 2011, it was announced that Leonard would co-star as Paul Verrall in the 2011 Broadway revival of "Born Yesterday" beginning in March.