Notharctus is a genus of adapiform primate that lived in North America and Europe during the late to middle Eocene.

[1] The body form of Notharctus is similar to that of modern rats.

Its fingers were elongated for clamping onto branches, including the development of a thumb.

Its spine is flexible and the animal was about 40 centimetres (16 in) in length, excluding the long tail.

[1] Fossils from at least seven other potential species have also been discovered.