I just stumbled across this wiki site for the various HELLBOY series:

http://hellboy.wikia.com/wiki/The_Hellboy_Universe_Comics



I love the HELLBOY stories by Mignola. But it does get a bit difficult to keep track of all the limited series and one-shots. And which ones are Mignola work, and which are apocryphal works by other artists.

This site allows you to navigate through all these, and see everything that was published at a glance, and in what order.

I was lucky, I first got into HELLBOY in 2002-2003 and got all 5 collected editions up to that point:
1. SEED OF DESTRUCTION,
2. WAKE THE DEVIL,
3. THE CHAINED COFFIN AND OTHER STORIES,
4. THE RIGHT HAND OF DOOM
5. CONQUEROR WORM

At that point they didn't even number them, and I numbered them on the bags I keep them in. I completed reading them and was all pumped up for the first 2004 movie right before it came out. That delightfully, wasn't a disappointment, and in fact was quite good and consistent with the comics series.

It used to be all Mignola story and art. Now two thirds of the new material, at least, is by other artists.

Mignola's HELLBOY is among the last series that is consistent and that I still enjoy as one of the best things published in comics.