Captain Frederic John Walker, CB, DSO & Three Bars (3 June 1896 – 9 July 1944) (his first name is given as Frederick in the Oxford Dictionary of National Biography and some London Gazette entries) was a Royal Navy officer noted for his exploits during the Second World War. Walker was the most successful anti-submarine warfare commander during the Battle of the Atlantic and was known more popularly as Johnnie Walker (for the Johnnie Walker brand of whisky).