1. Maj Mysteriet (1991)

This is the first album of the Danish comic series the dimensional detective. This first part, roughly translated as The Mystery of the 1. Mai, starts with introducing the concept of alternate dimensions (albeit they are partly parallel dimensions, as all characters have doubles in each dimension) and an interesting murder mystery. The main character, a detective, has been summoned by a meeting of his doubles. One of them has been murdered, and the murderer is one of them too.

The charm of this comic isn’t the alternate dimensions concept per se, as most of the alternate worlds are pretty standard for Alternative History fiction and in general follow the template that most alternates are depicted as less appealing than our world. Not much inventiveness there. What makes this really appealing is the character interaction, the many doubles of different characters testing each other to see how they differ and how they are the same.