You know, encyclopedic series are all well and good, but sometimes it's nice to have an outsider's eye, one that isn't tied to a specific era, company or editorial agenda. For example, Jeff Rovin's Encyclopedia of Super-Heroes (1985) has served me well as a reference despite being more than 20 years out of date. Covering super-heroes from every company, era, country and medium, Rovin's book can't show illustrations for every character, but does describe their costumes textually. There's an efficient biography, basic details like alter ego, first appearance and occupation, a quote from the character, and a brief comment that might cross-reference the character with another, or what it owed its popularity to. Black and white covers are sometimes reproduced and there are colors inserts as well. For example, this is how I first met Fatman the Human Flying Saucer, Super Green Beret and indy hero Captain Guts who apparently has the power to ejaculate with the "force of 10 fire hydrants".
There are characters from tv, movies, pulps, advertising, toys, folklore... everywhere. There are separate appendices to cover teams, obscure Golden Age heroes, minor superheroes (like seat belt safety advocate Beltman) and even the superheroes featured in Dial H for Hero. For today's readers, it may prove useful to get a peek at Golden Age characters either fallen into the public domain (Project Superpowers, Next Issue) or whose owners are desperate not to allow to (The Twelve). See the Green Llama BEFORE Alex Ross screwed him up!
Two years later, Rovin (former editor-in-chief of the Weekly World News, wow) came up with the Encyclopedia of Super Villains. This one I never did read cover to cover (it's pretty minty, in fact), but it's in the same style as the first one. Of course, at roughly the same size, it can't possibly be as complete. Most heroes have spawned a great number of recurring and one-shot villains, so a real survey would be huge. This Encyclopedia doesn't try to be bite off more than it can chew. There isn't even an appendix of obscure villains, for example. Instead, it tries to give a little bit of everything, including one-hit-wonders, Disney villains and mean-looking action figures.
Rovin later published Encyclopedias of Monsters and Cartoon Animals, but the subject matter didn't interest me as much and I never got them. Did anyone?