L21

L21 may refer to:

Vehicles

 * Aircraft
 * Albatros L 21, a German biplane bomber
 * Daimler L21, a German sports aircraft
 * LZ 61 (L 21), an airship of the Imperial German Navy
 * Piper L-21 Super Cub, an American aircraft


 * Ships
 * HMS L21, a submarine of the Royal Navy
 * HMS Viceroy (L21), a destroyer of the Royal Navy
 * INS Guldar (L21), a landing ship of the Indian Navy
 * SOVIET SUBMARINE L-21
 * SPANISH SHIP Castillia

Other uses

 * 60S ribosomal protein L21
 * Kete language
 * Ribosomal protein L21 leader
 * USA-193, an American satellite