The primary (and natural) moon of Warhammer Fantasy. Meaning "Beloved of Manann" in Old Reikspiel in reference to the human god of the sea, Manann, due to the effect it has on tides. The Lizardmen refer to it as the Silvered One. It's presumably a fairly normal sphere of rock and regolith. It is associated with many different gods, primarily among them being the High Elf god Lileath. Cathayans call it Yuejin and that its fullness is a sign of the Moon Empress' displeasure. Nehekhara referred to it as the moon goddess Neru, who is in challenged by Sakhmet. When its unnatural twin, Morrslieb eclipses it, you're in for one wild night. More specifically Geheimnisnacht and Hexensnacht, Halloween and New Years Eve respectfully.
Mannslieb miraculously survived the End Times completely unharmed. Though, to be fair, after the destruction of the World that Was into space debris, Mannslieb is basically just a big rock floating into space, probably getting pummeled by all the remains of the old world.
When Dracothion recreated the World-That-Was as the Realm of Azyr, Sigmar built his capital city, Sigmaron, on top of Mannslieb. He built on top of his personal palace spire, Sigmarion, an artificial star he called "Sigendil". It also looks like a massive lamppost from afar, which is hilarious.