Lachlan may refer to:
People Lachlan (name), masculine name
Places Several places in New South Wales, Australia, named for Lachlan Macquarie. For a more complete list, see Places named after Macquarie Electoral district of Lachlan, an electoral district of the Legislative Assembly in New South Wales, Australia Electoral district of Lachlan and Lower Darling, an electoral district of the Legislative Assembly in New South Wales, Australia Lachlan River, a river in central New South Wales, Australia Lachlan Shire, a local government area in the central west of New South Wales, Australia Lachlan Valley Railway, a rail preservation society based at Cowra, New South Wales, Australia Lachlan Valley Way, a state highway in New South Wales, Australia Upper Lachlan Shire, a local government area in the state of New South Wales, Australia Lachlan, Tasmania, a locality Lachlan Fold Belt Lachlan Island
Other Clan Maclachlan, a Scottish clan which is sometimes known as Clan Lachlan HMAS Lachlan (K364), a River-class frigate that served the Royal Australian Navy Young Lachlan, a schooner that was stolen and wrecked by convicts in 1819