Ruler (disambiguation)

A ruler is a device used to measure distances or draw straight lines.

Ruler may also refer to:
 * A person who wields significant or total political power
 * Ruler (film), a 2019 Indian Telugu-language action film
 * Ruler (gamer), stage name of League of Legends player Park Jae-hyuk
 * Ruler (horse), a racehorse
 * Golomb ruler, comprises a series of marks such that no two pairs of marks are the same distance apart
 * Slide rule, a mechanical analog computer
 * "Ruler", a song by Marnie Stern from This Is It and I Am It and You Are It and So Is That and He Is It and She Is It and It Is It and That Is That