The nerubian queen was a powerful creep in Warcraft III. Queens are both leaders and mothers to their subjects. It is rumored that nerubian queens can genetically pass knowledge from mother to daughter.
It was speculated that one would appear in an Azjol-Nerub dungeon or raid in Wrath of the Lich King. However, with the release of the expansion this proved to not be the case. No queens are seen, undead or otherwise.
A nerubian community has one leader, the nerubian queen. The leader is usually the eldest female, mother of much of the group. Large communities will have the elders elect one of their own to lead as queen. Groups formed for a specific purpose, such as a warband or aggregate of decimated families, will choose a leader with proven ability. Queens are the mothers of the cities. Most combine tactical skill with arcane might. Queens may also get quite large. Queens are usually aristocrats, healers, and/or wizards. Queens have something akin to genetic memory, transferred through arcane memory from mother to daughter.
The most ancient of queens can reach 40 feet in height and fill an entire cavern with their bloated bodies. Nerubians claim that an individual nerubian's power can be safely estimated by its size — so these very large queens are also very, very powerful.