Tempel–Tuttle (commonly known as Comet Tempel–Tuttle) is a comet that was independently discovered by Ernst Tempel on December 19, 1865 and by Horace Parnell Tuttle on January 6, 1866.

It is the parent body of the Leonid meteor shower. In 1699, it was observed by Gottfried Kirch but was not recognized as a periodic comet until the discoveries by Tempel and Tuttle during the 1866 perihelion. In 1933, S. Kanda deduced that the comet of 1366 was Tempel–Tuttle, which was confirmed by Joachim Schubart in 1965.

The orbit of 55P/Tempel–Tuttle intersects that of Earth near exactly, hence streams of material ejected from the comet during perihelion passes do not have to spread out over time to encounter Earth. This coincidence means that streams from the comet at perihelion are still dense when they encounter Earth, resulting in the 33 year cycle of Leonid meteor storms. For example, in November 2009, the earth passed through meteors left behind mainly from the 1466 and 1533 orbit.(3)

55P/Tempel–Tuttle is estimated to have a nucleus of mass 1.2×1013 kg(4) and radius 1.8 km(4) and a stream of mass 5×1012 kg