Opportunity Knocks was a UK television talent show originally hosted by Hughie Green.

The original radio version started on the BBC Light Programme in 1949 but moved to Radio Luxembourg in the 1950s. It was shown on ITV in 1956, produced by Associated Rediffusion, and from 1961 until 1978, produced by ABC. It was revived by the BBC from 1987 to 1990. Entertainers who appeared included: Mary Hopkin, Bonnie Langford, Les Dawson, Little and Large, Bobby Crush, Peters and Lee, Lena Zavaroni, Frank Carson, Max Boyce, Pam Ayres, Freddie Starr and Freddie Davies.

Bob Monkhouse presented the programme on BBC1 from 1987 to 1989, during which time it was called Bob Says Opportunity Knocks. A further series followed in 1990 fronted by Les Dawson. The theme song was Star by Kiki Dee.

A popular winner from Northern Ireland was Gregg Davidson, who went on to work for Beirut TV and now works locally as a Cabaret artist. He accompanied Chris De Burgh in Belfast. Gregg now resides in Carrickfergus.