The Aero L-39 Albatros is a high-performance jet trainer developed in Czechoslovakia by Aero Vodochody. It was designed during the 1960s as a replacement for the Aero L-29 Delfín as a principal training aircraft. It was the first trainer aircraft to be equipped with a turbofan powerplant. The type was exported to a wide range of countries as a military trainer.

The L-39 Albatros later served as the basis for the updated L-59 Super Albatros, as well as the L-139 (prototype L-39 with Garrett TFE731 engine). A further development of the design, designated as the L-159 ALCA, entered production in 1997. To date, more than 2,800 L-39s have served with over 30 air forces around the world. The Albatros is the most widely used jet trainer in the world; in addition to performing basic and advanced pilot training, it has also flown combat missions in a light-attack role. The design never received a NATO reporting name.

At the Farnborough Airshow in July 2014, Aero Vodochody announced the launch of the L-39NG, an upgraded and modernised version of the L-39.