Grand Librarian Maelin  

There are multiple NPCs named Grand Librarian Maelin in several zones.

In the Plane of Knowledge he spawns at +5, +1015, +389.85. He is not in the Find window, however it will get you close. Walk to Wanderer Kedrisan via the Find window. Turn northeast. That alcove immediately in front of you is an elevator. It has a massive up/down button on the corner of the alcove closest to you. Grand Librarian Maelin is in the room at the top at the bookshelf behind the large table.