[Morgeruat]

let's see, Melf, Otiluke, Tasha, Otto, Bigby, Nystul, Tenser, Leomund, Evard, Rary, Mordenkainon, Dramij, and Serten were all originally Greyhawk characters, some such as Mordenkainen and Melf were actual gamers at Gary Gygax's table (IIRC Mordy was gary's son) one or two may have come from various dragon amgazine articles before 2nd ed D&D came out.

Larloch is a powerful lich in Forgotten Realms, known to be allied with Szass Tam, the Zulkir of Necromancy, and leading contender for sole rulership of Thay.

Aganazar, and Abi Dalzim I know naught of, their spells were introduced in forgotten Realms literature, in the case of Aganazar, and in the Tome of magic for Abi Dalzim, who probably saw first printing in Dragon magazine.