Aeneas Lionel Acton Mackintosh (1 July 1879 – 8 May 1916) was a British Merchant Navy officer and Antarctic explorer, who commanded the Ross Sea party as part of Sir Ernest Shackleton's Imperial Trans-Antarctic Expedition, 1914–17. The Ross Sea party's mission was to support Shackleton's proposed transcontinental march by laying supply depots along the latter stages of the march's intended route.