William McLellan or MacLellan may refer to:
William McLellan (Australian politician) (1831–1906), mining agent and politician in colonial Victoria William McLellan (Scottish electrical engineer) (1874–1934), known for contributions to hydroelectric power William McLellan (American electrical engineer) (1924–2011), known for contributions to nanotechnology William McLellan (sea captain) (1735 – July 28, 1815), American merchant sea captain William Walker McLellan (1873–1960), founder of McLellan Stores William H. McLellan (1832–1912), American lawyer and politician Sir William Maclellan (knight) (15th century), Scottish nobleman William MacLellan, 4th Lord Kirkcudbright (c. 1647–1668), Scottish peer William MacLellan, 6th Lord Kirkcudbright (c. 1690–1762), Scottish peer
See also William E. McLellin (1806–1883), early leader in the Latter Day Saint movement