rec.arts.comics.misc - join
Comic books, graphic novels, sequential art.
Low activity, 641 subscribers, Usenet

rec.arts.comics.marketplace - join
The exchange of comics and comic related items.
Low activity, 464 subscribers, Usenet

rec.arts.comics.dc.universe - join
DC Comics' shared universe and characters.
Medium activity, 1356 subscribers, Usenet

rec.arts.comics.marvel.universe - join
Marvel Comics' shared universe and characters.
Medium activity, 1277 subscribers, Usenet

rec.arts.comics.strips - join
Discussion of short-form comics.
High activity, 642 subscribers, Usenet

rec.arts.comics.info - join
Reviews, convention information and other comics news. (Moderated)
Low activity, 67 subscribers, Usenet

alt.comics.alternative - join
You could try a book without pictures, for example.
Low activity, 40 subscribers, Usenet

rec.arts.comics.dc.vertigo - join
Comics from the Vertigo imprint.
Low activity, 118 subscribers, Usenet

rec.arts.comics.dc.lsh - join
The Legion of Super-Heroes and related characters.
Low activity, 143 subscribers, Usenet

rec.arts.comics.creative - join
Comics-related original creative writing. (Moderated)
Low activity, 112 subscribers, Usenet