While stationed at Fort Myer, Virginia, he appeared as Lieutenant Cable in the American Light Opera Company production of South Pacific, 1963 at Trinity Theatre in Georgetown.
[2] In 1971 he made his debut at the San Francisco Opera as the Duke of Mantua in Giuseppe Verdi's Rigoletto with Robert Mosley in the title role.
He returned to San Francisco twice more during his career, portraying Curly in Carlisle Floyd's Of Mice and Men in 1974, and a soldier in the United States premiere of Viktor Ullmann's Der Kaiser von Atlantis in 1977.
In 1979 he portrayed Prince Florian in the Opera Company of Philadelphia's production of John Philip Sousa's The Free Lance.
[6] Danner has appeared as a guest star on several television programs, including Ally McBeal, Chicago Hope, Law & Order: Special Victims Unit, NYPD Blue, Scrubs, and Touched by an Angel.