Alexander Montgomery Carlisle, PC (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 area of responsibility was the ships' safety systems such as the watertight compartments and lifeboats.
As a Privy Councillor, he was known as "The Right Honorable".
He ended his involvement in the Olympic class liners and retired in 1910 due to an argument with Lord Pirrie over the number of lifeboats required for a vessel of this size.
Pirrie, the chairman of Harland and Wolff, was satisfied that the number of lifeboats supplied more than met the board of trade regulations.
Carlisle then retired and did not have anything more to do with shipbuilding.
Thomas Andrews, Pirrie’s nephew, was then made master shipbuilder.
The Olympic class liners were the last ships that Carlisle was involved with.