Adriaen Thomasz. Key (c. 1544 – 1589) was a Flemish painter, draughtsman and printmaker active in Antwerp. He is most known for his specialty work on portraits and altarpieces. Little is known of his early life. He is believed to have been born in Antwerp in 1544. He trained for a time under glass painter Jan Hack III, and was registered as a pupil at the Antwerp Guild of Saint Luke in 1558. It may have been as early as this that he was employed by Antwerp painter Willem Key. He would eventually take over the shop, but the two were not related: in fact, he adopted his former employer's surname when he took over the shop in 1567; previously he went by Adreaen Thomasz., or Thomaszoon. It was that year that he was admitted to the Guild as a master painter. He appears to have been very politically nimble. Despite his Calvinist beliefs, he remained in Antwerp and took students during and after the Spanish sack of the city in 1585; despite remaining there, he received commissions from William of Orange (leader of the Dutch Revolt.) His death in or after 1589 is supposed due to his disappearance from the historical record at that point: it is not actually known that he died then, or simply finally abandoned the city.