Frederick Augustus Alexander (30 December 1870 – 20 April 1937) was a South African international rugby union player.

Born in Malmesbury, Cape Colony he attended Kimberley Boys' High School before playing provincial rugby for Griqualand West (now known as the Griquas).

He made his only two Test appearances for South Africa during Great Britain's 1891 tour.

Alexander was selected to play as a forward in the 1st and 2nd matches of the series, both of which South Africa lost.

[1] Alexander died in 1937, in Johannesburg, at the age of 66.