What was Mark Twain's real name?

Mark Twain’s real name was Samuel Langhorne Clemens. Mark Twain was a pen name used by the American writer, humorist, lecturer, and essayist best known for The Adventures of Tom Sawyer and Adventures of Huckleberry Finn.

Clemens was born in 1835 in Florida, Missouri, and grew up in Hannibal, a Mississippi River town that later inspired settings in his fiction. Before becoming a celebrated author, he worked as a printer and newspaper writer and trained as a steamboat pilot. His river experience shaped the name “Mark Twain,” a call used to indicate a measured depth of two fathoms—about 12 feet—considered safe water for a vessel.

The name was not his only pseudonym: he also wrote under names such as Josh and Thomas Jefferson Snodgrass. Still, Mark Twain became the enduring literary identity. The distinction matters because Samuel Langhorne Clemens is the person’s birth name, while Mark Twain is the famous professional name associated with American literary realism and works including Life on the Mississippi.