The Laurence Olivier Award for Best Actor in a Play is an annual award presented by the Society of London Theatre in recognition of achievements in commercial London theatre.

The awards were established as the Society of West End Theatre Awards in 1976, and renamed in 1984 in honour of English actor and director Laurence Olivier.

This award was introduced in 1985, as Actor of the Year, then retitled to its current name for the 1993 ceremony.

Prior to this award, from 1976 to 1984 (and again in 1988), there was a pair of awards given each year for this general category, one for Actor of the Year in a New Play and the other for Actor of the Year in a Revival.

Note: The below awards and nominations include individuals awarded and nominated under the now-defunct categories Actor of the Year in a New Play and Actor of the Year in a Revival as well as the current combined Best Actor category.