Messier 105 or M105, also known as NGC 3379, is an elliptical galaxy 36.6[2] million light-years away in the equatorial constellation of Leo.

It was appended when Helen S. Hogg found a letter by Méchain locating and describing this object which matched those aspects under its first-published name, NGC 3379.

[10] Observation of giant stars in the halo indicate there are two general populations: a dominant metal-rich subpopulation and a weaker metal-poor group.

[11] The galaxy has a weak active galactic nucleus of the LINER type with a spectral class of L2/T2, meaning no broad Hα line and intermediate emission line ratios between a LINER and a H II region.

[13] This galaxy, along with its companion the barred lenticular galaxy NGC 3384, is surrounded by an enormous ring of neutral hydrogen with a radius of 200 kiloparsecs (650 kilolight-years) and a mass of 1.8×109 M☉ where star formation has been detected.