When Goliath died in Civil War, many fans said he didn't matter because he was a "C-Lister" or even a "D-Lister.'' This is of course far from the only times fans (and occasionally, writers) have used such a term (or similar ones such as "second rater" or "third stringer") to describe different kinds of superheroes. But it got me to thinking: exactly what defines a character as being of a particular rank? And how many ranks are there?
I think we can look at it in two ways: in terms of popularity, and in terms of how competent they are.
In popularity, my guess is that the ranks would go like this:
A-List: These are character who can support their own series, and have done so for a long time. Superman, Batman and Wonder Woman are the classic examples. (Teams can also be rated this way; the Justice League has always been considered an A-Rank class team, even when composed mostly of lower-rank heroes, except perhaps during the Detroit League era.)
B-List: This covers most other characters and teams that currently have their own series, or had one not long ago.
C-List: These would be characters that don't have their own series, or did a long time ago. Goliath, in this sense, was a C-lister.
D-List: These characters are not believed to be able support their own series and have never had one- though a good writer can often come up with a "take" on them that turns out to be popular enough to suddenly earn them one, therefore going from D to B class. Many X-Men characters are examples of this.
Now, looking at them in terms of competency:
A-List:A hero who is considered to be among the best in his or her world, due to his power, intelligence, influence, etc. Superman and Batman (despite his lack of powers) definitely go in here.
B-List: These are the average heroes. They aren't that impressive (at least when compared to other heroes!) but there's nothing wrong with them. Most superhero team members are B-listers; Goliath was one as well.
C-list: There's something wrong with these characters. Nothing too bad, but they don't come across as competent or trustworthy as the others. Maybe they have a bad attitude that lands them in trouble often, or just don't have that much power. She-Hulk, at one point, was definitely a C-lister- she pretty much just punched people and hit on the male heroes (of course, since then, she's been rewritten as an Ace Lawyer.)
D-list: These are the truly incompetent heroes. They either have useless powers, or they're just plain stupid. These are usually (but not always) humorous characters. The Great Lake Avengers definitely go in here (though in some versions, they're more like C-listers.)
Note that these two lists are NOT always equivalent! The Martian Manhunter, for example, in between being a founder and pillar of the Justice League, having more powers than Superman and being highly intelligent and responsible, is definitely an A-lister within the DC Universe, but has never quite been one in terms of comic book popularity.
Of course, characters CAN move up (or down) on either of these scales; it all depends on the writing (and the whims of the public.)