Alexander Montgomery Carlisle (8 July 1854 – 6 March 1926) brother-in-law to Viscount Pirrie, was one of the men involved with designing the Olympic class ocean liners in the shipbuilding company Harland and Wolff. His main role of responsibility was the ships safety systems such as the watertight compartments, lifeboats, etc. As a Privy Councillor, he was known as "The Right Honorable".
He ended his involvement in the designing of the Olympic class liners and retired in 1910 due to an argument with Lord Perry over the amount of life boats required for a vessel of this size. Lord Perry was satisfied the amount of life boats supplied more than met with the board of trade regulations. Alexander then retired and did not have anything to do with ship building again. Thomas Andrews (Lord Perry’s nephew) was then made master ship builder. The Olympic class liners would be the last ships that he would ever be involved with.