Caistor Grammar School is a selective school with academy status in the English town of Caistor in the county of Lincolnshire, England. The school was founded in 1630. It has since grown to be one of the most respected and highest performing schools in the East Midlands. The school has been awarded specialist sports and humanities status. The school attracts students from not only the town of Caistor, but also several surrounding settlements, including Grimsby, Brigg and Market Rasen. The current Headteacher is Shona Buck, who took up the position in September 2022, becoming the school's 28th head. Caistor Grammar was ranked first in Lincolnshire at both GCSE and A Level results in 2017. The school was ranked first at GCSE in 2018 and first at A level and GCSE in 2019. In the 2017 Times newspaper league tables it is in the top ten mixed state schools in the country. The school was named Sunday Times Parent Power State Secondary School of the Year 2018 in November 2017 and was the named the top school in the East Midlands by the Sunday Times in November 2019. It was also named school of the decade in the East Midlands in 2020.

Vivian Hollowday, GC, sometimes known as Bob Hollowday, was a British recipient of the George Cross, the highest British award for gallantry not in the face of the enemy. He was the first non-commissioned member of the Royal Air Force (RAF) to receive this honour.