In 1991, Olsen appeared as
George Grossmith (the original Gilbert and Sullivan comic lead) in a one-man show called
A Song to Sing, O, which had been written for John Reed in 1981. Olsen's production opened in
Victoria in June 1991 followed by a tour including South Australia and Western Australia (July) and the
Australian Capital Territory and
Queensland (September). He directed
Trial by Jury and played the Learned Judge in the
Sydney Festival's 1997–98 production. In October 2000 in Melbourne, Olsen appeared in the Production Company's presentation, in association with the Melbourne Festival, of
The Gilbert & Sullivan Show, which represented a family party with some of the family members gathering in a parlor and singing Gilbert and Sullivan songs to entertain the other family members at the party. Appearing with the Gilbert & Sullivan Society of South Australia, Olsen sang the roles of Major-General Stanley in their 2004 production of
The Pirates of Penzance and Bunthorne in their 2006 production of
Patience. He also appeared in their concert production,
An Evening with Dennis Olsen, to celebrate the 125th anniversary of the Law Society of South Australia in 2004. Olsen is a popular exponent of
Noël Coward and appeared in a one-man combined Noël Coward/Gilbert & Sullivan show, as well as a Coward production,
Marvellous Party!, with
Amanda Muggleton at the Cremorne Theatre of the
Queensland Performing Arts Centre. In July 2006, he played the role of
Antonio Salieri in the production of
Peter Shaffer's
Amadeus in Perth. He has also appeared in cabaret and on radio. ==Honours==