Apocalypse: I Was Possessed by a Monster

I Want a Possession Story

It can involve possessing all kinds of monsters, objects, ghosts, and the like. Transforming via cards is fine too.

Novels Where the Protagonist Gradually Becomes Less and Less Human, or Less Like a Normal Creature

Looking for books like The Guest, Your Mom's Tentacles Are Crying! The stranger the better, like Dr. Apple in The Guest, Your Mom's Tentacles Are Crying! (either her battlefield form or her true form).

The Protagonist Is a Strange Creature or Can Transform into One

The Male Lead Gets Infected and Controlled, Changing Until He's No Longer Human

The Protagonist Has Two Identities: One Human, the Other a Demon or Supernatural Entity

The Male Lead Can Transform Into a Monster and Change Back Whenever He Wants

The female lead can be present or not, but the male lead must not be a bleeding heart.

The Protagonist Fuses with an Eldritch Creature and Undergoes Strange Changes

Possession, Body Snatching, and Control Stories

Are there any stories about possession, body-snatching, or mind control?

Possession and Body Snatching Stories

Any Stories About Someone Becoming a Parasite That Controls People?

A Male Lead Who Possesses Someone, Like Venom

The male protagonist possesses someone, like Venom.