Realm of Nothingness

The Realm of Nothingness is the fourth and final realm in the Kingdom Hearts games. Nothing exists here and if one stays here too long, they will not exist either. The only way to survive here is to remember your past. It is unknown if this realm has chosen a keyblader or not. If so it is most likely Roxas.

Diz
After being banished from Hollow Bastion by Xehanort, Barig, Dilan, Even, and Lenzo, Ansem the Wise wandered into the Realm of Nothingness and became Diz. Diz only survived here by remembering his past.

Trivia

 * Of the four realms, this is the only one Sora has not yet visited.