Maroussi B.C. alternately translated as Marousi, Amaroussi, or Amaroussion, is a professional basketball club that is based in Marousi, a northern suburb of Athens, Greece. The club's full name is Gymnastikos Syllogos Maroussi Basketball Club, which is commonly abbreviated as G.S. Maroussi B.C.

Marousi or Maroussi, also known as Amarousio (Αμαρούσιο), is a city and a suburb in the northeastern part of the Athens urban area, Greece. Marousi dates back to the era of the ancient Athenian Republic; its ancient name was Athmonon (Ἄθμονον) and it represented one of the 10 Athenian sub-cities. The area held a main ancient temple, where Amarysia Artemis, the goddess of hunting, was adored. Consequently the city's modern name derives from that of the goddess, Amarysia, which denotes the origin of the worship back in Amarynthos, Euboea. Its mayor is Theodoros Ampatzoglou, re-elected in 2023.