Name the celebrated actor who played the leading role in the first production of John Osborne’s The Entertainer (1957).

The correct option is Laurence Olivier.

John Osborne's groundbreaking play The Entertainer premiered at the Royal Court Theatre in London in 1957. The lead character, Archie Rice, is a failing, cynical music-hall performer who serves as a metaphor for the decline of the British Empire.
Laurence Olivier, already one of the most famous and acclaimed classical actors of the 20th century, took on the role of Archie Rice. Olivier's performance was highly celebrated, helping to bridge the gap between traditional theatre and the new wave of "Angry Young Men" playwrights like Osborne. Olivier later reprised the role in the 1960 film adaptation.