The Hall of Heroes is a selection of fourteen NPCs with stats and in-depth descriptions and histories. Seven of them are in the City of Greyhawk itself (remember this was published at a time before the Greyhawk Wars, so it's still theoretically set in CY 576), and the rest are from further afield in the Flanaess.
The trouble is, most of these NPCs are not ones that the PCs are ever likely to encounter, at least on a regular basis. Thus, their inclusion in the book is something of a mystery. We have:
- Nerof Gasgol, Lord Mayor of Greyhawk
- Derider Fanshen, constable in Greyhawk (also a 12th level cleric of Pelor)
- Sental Nurev, Captain-General of the Watch in Greyhawk
- Org Nenshen, Master of the Thieves Guild in Greyhawk
- Turin Deathstalker, Master of the Assassins Guild in Greyhawk
- Ren o' the Star, Master of the Traders Union in Greyhawk
- Jaran Krimeeah, lord of the Valley of the Mage
- Tysiln San, First Protector of the Valley of the Mage
- Korenth Zan, Father of Obedience of the Scarlet Brotherhood
- Alesh Marin, member of the Scarlet Brotherhood (in Stoink)
- Karll of Urnst, Duke of Urnst
- Tang the Horrific, Prince of the Clan (from the Dry Steppes, but now a wandering mercenary barbarian)
- Timitrios Spartakos, magic-user originally from the Great Kingdom, now in Greyhawk, and with a backstory tied to Jaran Krimeeah
- Guiliana Mortidus, cleric and member of the Horned Society
Of these, the DM isn't likely to really need the likes of the Lord Mayor and heads of the guilds of the city of Greyhawk (especially when they are covered in the City of Greyhawk boxed set, which appeared the year after this book was published), or the Duke of Urnst. Figures like the Mage of the Valley and the head of the Scarlet Brotherhood are deliberately supposed to be obscure, and detailing them here destroys their mystique.
The only ones that look to be particularly useful in a day-to-day sense are Derider Fanshen, Alesh Marin, Tang the Horrific, Timitrios Spartakos, and Guiliana Mortidus. Tang could be a terrific recurring character, one full of bluster and flash who storms onto the scene, steals it, and then bounds away. Guiliana could be a good long-term protagonist for a mid-level party (she's an 8th level cleric, and works as an agent for the Horned Society who's been sent on missions before, and has a band of underlings). Timitrios could be a good magic-user-for-hire; he's got some interesting quirks and a great backstory, with some built-in enemies that could spell trouble for anyone he's associated with (like the PCs).
On the whole, this is one of the least useful sections of the book. Five out of fourteen NPCs are useful in a day-to-day sense, which is a pretty bad percentage. Much of the art is recycled as well, which is doubly disappointing, but there are a few fun new pieces that do the job.