What are the names of the Companions who apostatized after the death of the Prophet, peace and blessings be upon him, and those who falsely claimed prophethood?

The Companion (Sahabi) is defined as one who met the Prophet, peace and blessings be upon him, believing in him, and died upon that faith. Hypocrites and apostates are excluded from this definition. In the era of the Prophet, peace and blessings be upon him, there were hypocrites who claimed companionship. The Prophet, peace and blessings be upon him, mentioned that among his Ummah there would be twelve hypocrites who would not enter Paradise. Hudhayfah ibn al-Yaman was the keeper of the Prophet's secret concerning them and knew their names. There was an indirect reference to one of them, "Ar-Rajjal ibn 'Unfuwah," who later apostatized.