The Л (L) was a series of 2-10-0 freight locomotives designed at Kolomna in World War II. Series production only started in 1945, but by 1955 a total of 4,200 had made it the most numerous steam locomotive of the SŽD. It was based on the FD 2-10-2, but had no trailing axle. The requirements included that it had to be suited for all lines in the country. Additionally, the SŽD had specified a bar frame, so the facilities at the Kolomna works had to be modified to manufacture this type of frame. Another modern feature were Boxpok wheels.

The prototype was designated П-0001, where the П (P) stood for “Pobeda” (victory). It was soon renamed to Л in honor of Lev Lebedyansky, chief designer at Kolomna. This factory built 1,762 and Luhansk built 2,049, while Bryansk added 389 more. The design was also used as a basis of the 2-10-2 series ЛВ (LB). In 1967, around 2,300 Л were still on service. By 1987 their number had shrunk to around 100. A number have been preserved, of which five are still in working condition.