St Saviour’s Grammar School was a free grammar school for boys located in the borough of Southwark, south of the River Thames in London, England. It existed as a separate entity from 1559 until 1896, when it was amalgamated with St Olave’s Grammar School, which was renamed St Olave's and St Saviour's Grammar School For Boys.
The name is from the parish of St Saviour's, which was formed in 1543 from the amalgamation of St Margaret's and St Mary Magdalen’s parishes. The parish adopted the name St Saviour's from the recently dissolved Abbey of St Saviour in nearby Bermondsey. The parish then leased the former Priory of St Mary Overie, a dissolved Augustinian monastery, which then became known as St Saviour's Church and was destined to become Southwark Cathedral in 1905.
In 1559, St Saviour's parish sold a quantity of silver plate to fund a new sixty-year lease on the church from Lady Day, dated 6 June 1559. A condition of the lease was that within two years the parish would establish a building and employ a schoolmaster for a free grammar school. On 31 August 1559, the parishioners decided in the interim to run the school in the church house of the old St Margaret parish. This was funded by renting out the Lady Chapel of the priory to a baker, as well as selling the vestments and brass vessels of the parish.
On 16 May 1562 the parishioners paid £42 for a thousand-year lease from Matthew Smith on a building associated with the Green Dragon Inn, which had previously been owned by Lady Cobham. Under the first schoolmaster, Christopher Ockland, the school moved into this new home, known as Green Dragon Court, lying just south of St Saviour's Church and now part of the site of the Borough Market.