Though most people only know of him from his long year's playing Det. Lennie Briscoe on Law & Order, he really had a legendary stage career -- starring in the original productions such shows such as Carnival, Promises Promises (winning the Tony Award as Best Actor), Chicago (as the lawyer, Billy Flynn), and 42nd Street. Not to mention the voice of 'Lumiere the Candlestick' in the animated film Beauty and the Beast, which more young people probably know him for than anything. In fact, he holds the record for most performances by a leading actor in Broadway history.
And I would not be doing my alumni responsibilities probably if I didn't mention he went to Northwestern. (Though it's possible he may have left school early to go to New York.)
This comes from a TV special hosted by Tom Bosley in 1982, nine years before he began on Law & Order.