Colt 45 is a term used to designate two distinctly separate firearms produced by Colt's Manufacturing Company:

• The Single Action Army, also known as the Peacemaker—"the gun that won the West"
• The M1911, designed by John Browning and the official sidearm of the United States armed forces from 1911 to 1985

Colt 45 is also the name of a popular malt liquor brewed by the Pabst Brewing Company in the United States.

Colt 45 is also a brand of beer produced in Poland.

The Houston Colt .45's were a baseball expansion franchise that began play in the National League in 1962. In 1965, to coincide with the opening of their new indoor stadium (the Astrodome), the team was renamed the Houston Astros.