The Hospital and Free School of King Charles II, Oxmantown, also called The King's Hospital (KH; Irish: Scoil Ospidéal an Rí) is a Church of Ireland co-educational independent day and boarding school situated in Palmerstown, County Dublin, Ireland. It is on an 80-acre campus beside the River Liffey, called Brooklawn, named after the country houses situated on the site and in which the headmaster and his family reside. The school is also a member of the HMC Headmasters' and Headmistresses' Conference and the BSA.

Founded in 1669, it is one of the oldest schools in Ireland and was also known as the Blue Coat School. Although priority is given to those of the main Protestant denominations, as a Christian school, it is attended by students of other Christian denominations and other faiths. The school's colours are navy and gold. The school crest is three burning castles with the date "1669", almost identical to the crest for Dublin city. The current headmaster is Mark Wallace.

The school was founded in 1669 as The Hospital and Free School of King Charles II and was located in Queen Street, Dublin. King's Hospital was a continuation of the old Free School of Dublin. On 5 May 1674, the school opened with 60 pupils, including 3 girls.

During the early seventeenth and early eighteenth centuries, it was used as the site of elections to the Irish Parliament's Dublin City constituency. When this was changed to the Tholsel for the 1713 general election, it led to the Dublin election riot.

From 1783 to 1971, the school was located in Blackhall Place, Dublin, later the headquarters of the Law Society of Ireland in a building and amongst a street plan that was designed by the architect Thomas Ivory and encompassed much of what was previously the land of Oxmantown Green.

The take-over of Morgan's School (1957) contributed to steadily increasing numbers of students, and by 1970, a need for extra space and facilities led to the move from the city centre to a modern purpose-built school set in its own 100-acre (400,000 m²) site on the banks of the River Liffey in Palmerstown, County Dublin.

A 57-year-old manuscript by the Nobel Prize in Physics winning physicist Erwin Schrödinger resurfaced at the school in 2012. Entitled "Fragment From An Unpublished Dialogue Of Galileo", it was written for the school's 1955 edition of the annual Blue Coat magazine to coincide with Schrödinger leaving Dublin to take up his appointment as Chair of Physics at the University of Vienna. Schrödinger wrote the manuscript for the school's former English teacher and Editor of the Blue Coat magazine, Ronnie Anderson (now deceased), a friend of Schrödinger when he lived in Dublin. It is now in the possession of King's Hospital alumnus Professor Jonathan Coleman in CRANN at Trinity College Dublin.

The school is co-educational and caters for some 720 pupils, with 408 day pupils and 292 boarders in 2023/24. The King's Hospital has students from all over Ireland and from overseas. Students from Germany and Spain are the most common international students.^{[citation needed]}