King Edward VI Grammar School, or KEGS, is a British grammar school with academy status located in the city of Chelmsford, Essex, England. It takes pupils between the ages of 11 and 18, ie. school years 7 to 13. For years 7 to 11 the school is boys-only, whereas it is mixed in the sixth form (years 12 and 13).  The headteacher is Tom Carter, who was appointed in the autumn of 2014.
 KEGS was one of many grammar schools founded by  Edward VI. Its current form resulted from a royal warrant dated 24 March 1551, although evidence of this school exists from as far back as the 13th century, possibly earlier, as a chantry school in a different location in Chelmsford.  Indeed, the school of 1551 was merely a "rebranding" of the Chelmsford Chantry School, a Roman Catholic institution which had been abolished along with the monasteries during the English Reformation.  The school was moved to its present site on Broomfield Road in 1892. Once a boarding school, it was one of many grammar schools to join the state sector and abolish the nominal fees. The last boarding students left in the 1970s. In 1976 it admitted the first female pupil to the Sixth Form, to study Classics.
 The school has been ranked in the top 50 schools in the country in national examination league tables. KEGS was previously a Foundation School and Specialist Science College and Language College. The school converted to academy status in April 2011, but continues to have science and languages as specialisms. It is also a Leading Edge school.
 In 1981 it was named by The Sunday Times as the most successful state school as measured by Oxbridge open awards. In 1998, it was rated by the Financial Times as the most successful state school at GCE advanced level in the period 1993-1998. In 2001 the school was named Sunday Times School of the Year. The 2015 Good Schools Guide names KEGS as the top selective state school for a number of A-level subjects, as well as GCSE History and FSMQ Additional Mathematics. In December 2021, it was judged to be "outstanding" by OFSTED.
 In 1907, headmaster Frank Rogers set up the system of "Houses" – Holland, named for the translator Philemon Holland; Mildmay, for the courtier and politician Sir Walter Mildmay; Strutt, for the antiquary Joseph Strutt; and Tindal, for the lawyer Sir Nicholas Conyngham Tindal, and dividing the school into four forms in each year. Due to the expansion of the school roll over the last few years, this has not been the case. Instead, there are five forms, which contain a mix of people from different houses.
 The school maintains an Army contingent of the Combined Cadet Force (CCF), which was also open to students of Chelmsford County High School for Girls until 2017. Military music is provided within the contingent by a Corps of Drums playing drums, flutes and bugles. The Corps wears the full dress scarlet tunics of The Essex Regiment, incorporating the purple facings which gave the Essex Regiment its nickname 'The Pompadours'. It carries the drums of the 5th Battalion (Territorial Army) emblazoned with the Regiment's battle honours.
 The school has many ensembles, of which the orchestras include members from other schools, though the majority are from KEGS and Chelmsford County High School for Girls. The other ensembles are exclusive to those who attend KEGS.
 The KEGS Ambassador is the school's independent student newspaper. Since its creation in January 2009, it has featured numerous articles by alumni, staff and students.
 The KEGS Young Engineers team won the 2022 PAPI Raspberry Pi Competition in the years 12-13 division, as well as the People's Choice Award and has made it to the final every year since the competition started.[citation needed]
 The team competes in the FIRST Lego League Challenge, sending two year 8 and 9 teams every year, having gone to the finals numerous times, as well as a year 12 team annually to the Student Robotics competition where they have reached the quarter-finals multiple times.[citation needed]
 The KEGS Languages Society (Langsoc) is a group where both concepts in linguistics and the structure of specific languages are discussed, mostly in short presentations.
 Langsoc also provides training for the United Kingdom Linguistics Olympiad (UKLO). A notable success is of a student winning a gold medal in the International Linguistics Olympiad (IOL) in 2022.
 The KEGS Medical Society (MedSoc) is the society where topical medical issues are discussed.
 The KEGS Economics Journal is another of the school's student-led newspapers. They feature articles on a wide variety of national and international economic and political affairs.