Admiral Phillips Cosby (c. 1729 – 10 January 1808) was a Royal Navy officer who fought in the American Revolutionary War.

Cosby joined the Royal Navy as an ordinary seaman in 1747.

[1] He was given command of a schooner at the Siege of Louisbourg in 1758 and was present at the capture of Quebec in 1759.

[1] He was receiver general (treasurer) of the Caribbean island of Saint Kitts from 1771 to 1778, a lucrative post which he resigned on the outbreak of the Anglo-French War.

[2] In command of HMS Centaur in 1778, he took part in the Battle of Ushant and in command of HMS Robust in 1779, he took part in the Siege of Charleston in 1780.