Twain may refer to:

• The number 2 (dated or literary usage)

People

• Mark Twain, pen name of American writer Samuel Langhorne Clemens (1835–1910)

• Norman Twain (1930–2016), American film producer

• Shania Twain (born 1965), Canadian singer-songwriter

Places

• Twain, California, a census-designated place in Plumas County

• Douglas River, formerly named Twain, in New Zealand

Other uses

• TWAIN, a communication standard for computer software and digital imaging devices