Robert Callen MacKenzie SCR BCR (30 November 1948 – 24 February 1995) was an American professional soldier whose career included service as an infantryman in the United States Army during the Vietnam War, then C Squadron 22 (Rhodesian) SAS, the South African Defence Force, and the Transkei Defense Force.

As a contributing editor for unconventional operations for Soldier of Fortune (SOF) magazine, he was sent to cover conflicts in different hot-spots around the globe, including Mozambique, Central America, Croatia, Bosnia, Russia, Thailand, Suriname, Taiwan and Cambodia. At the time of his death, he was in command of and training the Sierra Leone Commando Unit (SLCU
In 1970, MacKenzie traveled to Rhodesia in Africa, and passing the rigorous selection course, enlisted as a foreign volunteer in the Rhodesian Special Air Service, where from then on until 1980, he rose through the ranks from Trooper to Captain and SAS Squadron Commander.

Decorations received during this time served with the Rhodesian SAS include the Bronze Cross of Rhodesia for “gallantry and determination in action” and the Silver Cross of Rhodesia for “conspicuous gallantry and leadership in action.” When the Rhodesian Bush War ended with the Lancaster House Agreement, MacKenzie resigned from the new Zimbabwe National Army and joined the South African Defence Force as a Special Forces Major. The following year, he joined the Transkei Defence Force as second-in-command, Transkei Special Forces Regiment. In 1985, after 15 years serving abroad, he returned to the United States.