Lieutenant-Commander Sir August Bernard Tellefsen Cayzer, 1st Baronet (21 January 1876 – 28 February 1943) was an English shipowner.
Cayzer was the third son of Sir Charles Cayzer, 1st Baronet, head of the shipowners Cayzer, Irvine & Co. He joined the Royal Navy as a Naval Cadet in HMS Britannia and served until 1902. He was promoted Lieutenant-Commander on the Emergency List in 1906. He was one of the earliest members of the Castaways' Club
On leaving the Royal Navy, he joined the family firm, later becoming chairman. He was also chairman of the Clan Line, Houston Line and Scottish Shire Line, as well as several other companies. He was a director of the Suez Canal Company.
Cayzer was created a baronet in the 1921 New Year Honours.