Alexander Macfarlane (1851–1913) was a Scottish logician, physicist, and mathematician.

Alexander Macfarlane may also refer to:

• Alexander MacFarlane (astronomer) (1702–1755), Scottish merchant, planter and astronomer

• Alexander Macfarlane (politician) (1818–1898), Canadian lawyer and politician

• Alex MacFarlane, Australian activist

• Sandy MacFarlane (1878–1945), Scottish football player and manager