Harem ,
Harem
harem mating is one male to several females.
eunuch
The harem keeper is the Sultan. In this regard he could be considered the head of the harem. The harem guards are eunuchs. An odalisque is a harem slave.
No, a horse herd is not called a harem it is just called a wild horse herd.
Walruses use their long tusks to fight with other males; the victorious male takes control of the harem.
As far as I know it's known as a male harem. Chinese Empress Wu Zetian (7th Cen. A.D.) was famous for having one.
There is no antonym for harem, but for anime and manga genres there is a genre called "reverse harem" where a girl is surrounded and/or wanted by multiple men.
He was a Eunuch
oda
A harem.