Roxas, the Key of Destiny (めぐりあう鍵 Meguriau Kagi?, lit Serendipitous Key) is the Nobody of Sora, and Rank XIII of Organization XIII. Like Naminé, he was born when Sora released his own heart in order to restore Kairi's. Although Sora's heart was soon restored, Roxas continued to endure and exist, oblivious to Sora's existence for most of his life. He has the ability to use the Keyblade, and wields light, using it to direct rays that strike opponents with great power. He commands the Samurai Nobodies. He is strong like Ventus, as Xigbar reveals in the Secret Reports.

Roxas was also one of the mysterious hooded figures in "Another side, Another story..." and "Deep Dive". During the prologue of Kingdom Hearts II, the player controls Roxas for a short time until Sora is awakened. Later in this same game, Roxas also acts as a minor antagonist. Roxas is the main protagonist in Kingdom Hearts 358/2 Days, which focuses on the time between Roxas's creation and when he leaves the Organization.