St. Olave's Grammar School (formally St. Olave's and St. Saviour's Church of England Grammar School) ( or ) is a selective secondary school for boys in Orpington, Greater London, England. Founded by royal charter in 1571, the school occupied several sites in Southwark, before establishing a location on Tooley Street in 1893. It moved to the suburb of Orpington in 1968, and has admitted girls to its sixth form since 1998.

A former Sunday Times State School of the Year (2008), the school is selective at both initial entry and for entry to the sixth form, but it has been criticised for policies that led to students being excluded from the sixth form for not achieving high grades. In 2017, parents threatened legal action against the policies applied by headteacher Aydin Önaç (who subsequently resigned), and the London Borough of Bromley instituted an inquiry whose critical report was published in July 2018.