Aleksin (Russian: Але́ксин) is a town and the administrative center of Aleksinsky District in Tula Oblast, Russia, located 71 kilometers (44 mi) northwest of Tula, the administrative center of the oblast.

Aleksin was sacked by Khan Akhmat in 1472 during his invasion of the Grand Duchy of Moscow.

During World War II, Aleksin was under German occupation from 29 November 1941 until 17 December 1941.

[12] On the night of 8–9 November 2024, during the Russo-Ukrainian War, Ukraine launched a drone attack on the Aleksin Chemical Plant—a subsidiary of state corporation Rostec—about 190 km (120 mi) south of Moscow, causing a series of explosions and fires at the plant which manufactures ammunition and explosives for the Russian military.

Cascading explosions at 1 p.m. due to chemicals catching fire from the earlier strikes led to authorities evacuating workers.