Sir John Markham (died 1479) was an English judge and Chief Justice of the King's Bench.
He and his elder brother Robert were both made knights of the Bath at the coronation of Edward IV.
On the accession of Edward IV he was immediately promoted to the office of chief justice of the king's bench, 13 May 1461, in place of Sir John Fortescue.
He was credited with having procured a knighthood for Yelverton, who had loked to have ben chef juge, to console him for his disappointment.
Fuller, who couples him with Fortescue as famous for his impartiality, tells us that the king deprived him of his office because he directed a jury in the case of Sir Thomas Cooke, accused of high treason for lending money to Margaret of Anjou (July 1468), to find him guilty only of misprision of treason.