The Aero L-39 Albatros is a high-performance, jet trainer aircraft developed in the Czech Republic to meet requirements for a trainer during the 1960s to replace the L-29 Delfín.

It was the first of the second-generation jet trainers, and the very first turbofan-powered trainer produced, and was later updated as the L-59 Super Albatros and as the L-139.

The design is still produced in an evolved state as the L-159 Alca, while more than 2,800 L-39s still serve with over 30 air forces around the world. The Albatros is versatile, seeing duty in light attack missions as well as basic and advanced pilot training, and is the most widely-used jet trainer in the world.

The L-39 first flew on 4 November, 1968, and was employed as the basic jet trainer for the Soviet Union, Czech Republic, and the rest of the Warsaw Pact nations (with the exception of Poland, who stuck with their first-generation TS-11 Iskra jet) from 1971 onward. The L-59, originally designated the L-39MS, a update to the design, re-engined with the DV-2 turbofan, remained in production until 1999.