William Alexander (13 June 1910 – 11 July 2000) was a leading activist within the Communist Party of Great Britain (CPGB), most known for commanding the British Battalion of the International Brigades during the Spanish Civil War.

[3] Later in life he became an author, the vice-chairman of the International Brigade Association, and the president of London's Marx Memorial Library.

Alexander was the son of a carpenter, born into a large working-class family in the rural English town of Ringwood, Hampshire.

[4][5][6] In spring of 1937, Alexander volunteered to join the British Battalion of the International Brigades to aid the Republican side in the Spanish Civil War.

[3] Alexander eventually rose to the rank of commander of the British Battalion and led his troops into combat during the Battle of Teruel.

[3] He attempted to join the Royal Military Academy Sandhurst early in World War II, initially being refused a place on account of his CPGB membership.