He also played Brendan Kearney, the village schoolmaster in Ballykissangel (1996–2001), and Danny Parsons, the unscrupulous (fictional) manager of pop group S Club 7 in their debut TV series Miami 7 (1999).
He has also appeared in two of the Pink Panther movies and his other film credits include Cry Freedom, Paper Marriage, Moll Flanders and Michael Collins.
Recent film roles were O'Connor in Villa of Roses and Declan Murphy in A Flight of Fancy.
Among Whelan's other television credits are Glenroe, Angels, Hideaway, Minder, The Royal and Kavanagh QC.
In 2005 he appeared in the BBC hospital drama Casualty@Holby City and in 2006 he starred in Channel 4's Goldplated.