185 Eunike is a dark and very large main-belt asteroid. It was discovered by C. H. F. Peters on March 1, 1878, in Clinton, New York and named after Eunike, a Nereid in Greek mythology whose name means 'happy victory'. The name was chosen to celebrate the Treaty of San Stefano (1878).

This object is orbiting the Sun at a distance of 2.74 AU with an eccentricity of 0.129 and an orbital period of 4.53 years. Its orbital plane is inclined at an angle of 23.2° to the plane of the ecliptic. Using infrared measurements, the diameter has been measured at 160.464 km. It has a primitive carbonaceous composition.

Based upon photometric observations made between 2010 and 2014, this asteroid has a rotation period of 21.812±0.001 hours and a brightness variation of 0.08±0.01 in magnitude. At opposition, the absolute magnitude was measured at 7.45±0.01. It displays a hemispheric albedo dichotomy similar to that on 4 Vesta.

As of 17 September 2020, there have been thirteen observed occultations of stars by Eunike.^{[citation needed]}