An ell (from Old Germanic *alinâ cognate with Latin ulna) is a unit of measurement, originally a cubit, i.e., approximating the length of a man's arm from the elbow ("elbow" means the bend or bow of the ell or arm) to the tip of the middle finger, or about 18 inches (457 mm); in later usage, any of several longer units. In English-speaking countries, these included (until the 19th century) the Flemish ell ( of a yard), English ell ( yard) and French ell ( yard), some of which are thought to derive from a "double ell".

Ell or ELL may refer to:

• Ell, a measure of length
• Ell, Luxembourg, a commune and town in Luxembourg
• Ell, Netherlands, a town in the Netherlands
• Ell (architecture), a wing of a building
• Ell (Scots), a Scottish measure of length
• ELL (gene) (elongation factor RNA polymerase II), a human gene
• Ell (surname), a family name
• Eldar Gasimov, Azerbaijani singer
• European Lunar Lander
• East London Line, a railway line that used to be part of the London Underground, that amalgamated with the London Overground in 2010.
• Encyclopedia of Language and Linguistics, a compendium of human communication
• English language learner, a person acquiring the English language
• A name for the letter L
• \ell, a LaTeX symbol ()

Stephen Elliott (November 11, 1771 in Beaufort, South Carolina – March 28, 1830 in Charleston, South Carolina) was an American legislator, banker, educator, and botanist who is today remembered for having written one of the most important works in American botany, A Sketch of the Botany of South-Carolina and Georgia. The plant genus Elliottia is named after him.