Lembit Oll (1966–1999) was an Estonian chess Grandmaster (GM). Born in Kohtla-Järve, he won the national championships of Estonia, the World U16 Championships, and World U18 Championships in his early career. A GM since 1990, he achieved commendable finishes in several high-profile tournaments, such as Hastings tournament, the 1990 Reggio Emilia Tournament, and the 1996 European Championship.
Oll was admired for his attacking style and specialized in pawn structure in his technical play. He was recognized for his skill in Sicilian Defence, particularly the Scheveningen Variation.
Oll's career was stained by personal struggles. Suffering from depression, he committed suicide on 17 May 1999. Posthumously, a memorial tournament was held in his honor in Estonia, his native country.