Millicent Serene, or Milli, is a resident of Eldre'Thalas mentioned by Rabine Saturna before the quest . She is the creator of the Fruit of Fertility, seen in Dire Maul East as the Felvine beside Alzzin the Wildshaper.
She cannot be found in the World of Warcraft.
Not much is mentioned in World of Warcraft about Milli, other than that she was able to "will the power of nature itself into potent artifacts she forged." The aforementioned Fruit of Fertility was one of such items, said to have granted Eldre'Thalas prosperity. and seem to be two other objects made by her, which are rewards of the quest started at Rabine Saturna after speaking to him about Dire Maul.