English: John Thornton of Coventry (fl. 1405-1433) was a master glazier and stained glass artist active in England during the 15th century. The output of his workshop includes some of the finest English medieval glass.

The first certain record of Thornton, apart from a possible 1371 reference in Coventry, is his 1405 contract with the Dean of York Minster to glaze the quire east window. The Archbishop of York at the time was Richard le Scrope, a former Bishop of Lichfield and Coventry, and the window was funded by Walter Skirlaw, also previously Bishop of Coventry, so it seems possible both men would have recommended Thornton based on their knowledge of his work in his home town.

Thornton was made a freeman of York in 1410, but was known to be back living in the St John's Bridges area of Coventry (now known as Burges) by 1413. He appears again in 1433, when he received further payment from the dean and chapter of York, and was recorded as holding property there.

Thornton's masterpiece is the Great East Window of York Minster, the largest in the building and containing about 1,680 square feet (156 m2) of glass. According to the contract, much of the work was to be executed by his own hand, though specifically only to "pourtray [...] the histories, images, and other things to be painted on the [window]"; evidently some of the glazing would be carried out by apprentices or workmen. Thornton is likely to have recruited glaziers locally in York: he seems to have been an enthusiastic teacher, and his style quickly became dominant in the area.

Work thought to be by Thornton can also be found in several smaller churches, as well as in St Mary's Hall in Coventry. His surviving windows for Coventry Cathedral were removed before it was destroyed in the Coventry Blitz and have been preserved. He is also thought to have produced the windows from the chapel at Hampton Court, Herefordshire, which are now dispersed in various collections, and seven panels in the Church of St. Mary Magdalene, Newark-on-Trent.