What if Xavier Never Formed the X-Men?
In these stories, the X-Men are in character, but their lives occur as if the X-men had never been.

Different Lifestyles
Stories in this category have the X-Men in situations or acting in manners uncharacteristic to how we know them. This is basically a category for writers to redesign the known characters to fit molds in which they would like to see them.

Children of the X
Stories here are about the children of the X-Men

Mutants of Other Times
These are stories about the lives of mutants in the past and future.

Mutants of Other Realities
Stories about Mutants from other realities.

Ordinary Mutants
Stories about everyday mutants with no super-hero attachments.

Humans
Stories about humans living in society with mutants.