228 Agathe is a stony main belt asteroid, about 9 kilometers in diameter.

It was discovered by Johann Palisa on 19 August 1882 at Vienna Observatory, Austria.

Photometric observations during 2003 showed a rotation period of 6.48 ± 0.01 hours with a brightness variation of 0.27 ± 0.03 in magnitude.

[3] Agathe is the lowest numbered asteroid to have an Earth-MOID as low as 0.657 AU (98.3 million km).

Agathe was named after the youngest daughter of Austrian astronomer Theodor von Oppolzer (1841–1886), professor of astronomy in Vienna.