What 3rd party books best round out Pathfinder?

[Herald]

Every so often in the Pathfinder Adventure Paths I see references to other books not printed by Paizo and I was considering perhaps getting a few to round out my games. Mostly these are Monster books. So what would be on the list.

I can assume that Tome of Horrors 3.5 should make the list.

I think I remember something from Green Ronin, but I can't remember what that was.

Anyone care to make suggestions?

[Lilith]

Tome of Horrors (I, II and III)
Advanced Bestiary
The Book of Fiends

So far, those are fairly common references.

[Krome]

Advanced Bestiary ROCKS!

[Shisumo]

Krome wrote:

Advanced Bestiary ROCKS!

It does indeed! My Rise of the Runelords PCs are going back to finish dealing with

Spoiler:

Vorel Foxglove and the Misgivings

because they didn't actually deal with the problem when they were there before, so I'm using the Advanced Bestiary all over everywhere to prepare a "proper" welcome for them...! Plaguemoss zombies and the dust wight manticore FTW!

[Herald]

Advanced Bestiary,

That was what I was looking for. Don't have a lot of Green ROnin stuff. Need to change that.

[Shinmizu]

OMG!

Spoiler:

Vorel Foxglove and the Misgivings!

I saw them when they were opening for Led Zepellin, man!

[Shisumo]

Shinmizu wrote:

OMG! ** spoiler omitted **I saw them when they were opening for Led Zepellin, man!

B*@#@*!~! Everybody says that, but it's always posers trying to pretend they were on the edge back then!