NGC 2266 is an open cluster of stars in the constellation of Gemini. It was discovered by German-British astronomer William Herschel on 7 December 1785. This is a relatively dim cluster with an integrated visual magnitude of 9.5 and an angular size of . The stellar members can be readily resolved with an amateur telescope. NGC 2266 is located at a distance of from the Sun. It is located close to the opposite part of the sky from the Galactic Center, or the anti-center.
This is a rich cluster that is well condensed. It is of intermediate age; similar to the ages of the Hyades and Praesepe clusters. However, it has a lower metallicity than either cluster. NGC 2266 has a heliocentric radial velocity of . A 2008 study found 12 variable stars in the field of this cluster, although they lie outside the cluster radius. A single candidate blue straggler has been identified.