Adventures into the Unknown
Adventures Into The Unknown was published by the American Comics Group (ACG) between Fall of 1948 and August 1967.
Adventures Into The Unknown was the first of its kind, a genre that would flourish at the hands of other publishers and creators as time wore on: it was the first of the horror/weird anthology titles. This particular type of comic book would capture kids' imaginations for decades to come, but here was its first appearance, tame though it might be according to modern standards. (It should be mentioned that the very first issue attempted a Gothic-horror connection with an adaptation of Walpole's Castle of Otranto.)
Like most anthology titles, AitU had no recurring characters for quite some time (although a continuing storyline, 'The Spirit of Frankenstein,' appeared early on in issues #5-16). This would change in the mid-1960's, possibly as a response to Marvel's success in the superhero field, with a character called Nemesis, whose adventures took over the title completely for several issues.
Like most of ACG's output, AitU was always competently executed, but still just mediocre enough to stay quietly in the background, trusty and reliable but not exciting; this was enough to sustain it for 174 issues and nearly two decades, though. It is interesting to note that this was one of the few such anthology titles to survive the 1950's purges begun after the introduction of the Comics Code: ACG's material was already tame enough, so that the censors had little to complain about from them.