Jára Cimrman (Czech pronunciation: [ˈjaːra ˈtsɪmr̩man]) is a Czech fictional character of a national giant. Created by Jiří Šebánek, Ladislav Smoljak and Zdeněk Svěrák, the fictional personality (universal genius, inventor, sportsman, criminalist, poet, writer and philosopher), Jára Cimrman won the voting for The Greatest Czech in 2005 (only the fact that Cimrman is fictional prevented him from actually winning). He is presented as one of the greatest Czech playwrights, poets, composers, teachers, travellers, philosophers, inventors, detectives, mathematicians and sportsmen of the 19th and early 20th century. Playing the game on his real existence is part of his characterization.

Cimrman made his first appearance on a regular radio programme Nealkoholická vinárna U Pavouka ("The Non-Alcoholic Wine Bar chez Spider") on December 23, 1966. Although the character was originally meant to be just a modest caricature of the Czech people, history, and culture, he became an immensely popular protagonist of modern Czech folklore, and an ersatz national hero. Cimrman is both the major character and the putative author of great number of books, plays, and films. Žižkovské divadlo Járy Cimrmana (Jára Cimrman Theatre in Žižkov) is one of Prague's most frequented theatre houses.