Alexander Cozens was a British landscape painter in watercolours, born in Russia, in Saint Petersburg. He taught drawing and wrote treatises on the subject, evolving a method in which imaginative drawings of landscapes could be worked up from abstract blots on paper. His son was the artist John Robert Cozens.

Alexander Cozens was born in St. Petersburg, Russia. Widely mistaken to be a natural son of Emperor Peter I of Russia and a British woman — Mary Davenport — from Deptford, he was, in fact, the son of Richard Cozens (1674–1735), who worked for Peter I as a shipbuilder. The emperor was the godfather of Alexander. He was educated in England from 1727, but later returned to Russia. In 1746 he sailed from St Petersburg to Italy, where he spent two years before travelling onward to England. While in Rome, he worked in the studio of the French landscape painter, Claude-Joseph Vernet. Between 1750 and 1754, Cozens was drawing-master at Christ's Hospital, and in the same decade also began to take private pupils. From 1763 to 1768 he was drawing-master at Eton College. He gave lessons to the Prince of Wales, Sir George Beaumont, and William Beckford, arguably, the three most important British art patrons and collectors of their generation. Beckford continued to correspond with him for some years. He also practised at Bath.

In 1760 he was among the contributors to the first public exhibition in London of works by living artists, held in the great room of the Society of Arts. The exhibition was organised by a body of artists who afterward divided into the "Free Society" and the "Incorporated Society of Artists". Cozens contributed to the exhibitions of both societies. In 1761 he obtained a prize from the Society of Arts at the exhibition in the Strand of the former, but he was one of the original members of the latter, incorporated in 1766. He also exhibited eight works at the Royal Academy between 1772 and 1781.

He married Charlotte Pine, the daughter of John Pine, Bluemantle Pursuivant in the College of Heralds. They left one son, John Robert Cozens, and a daughter, Juliet Ann Cozens (later Roberts). Alexander Cozens died in Duke Street, Piccadilly, London, on 23 April 1786.