Allah: He who has the Godhood which is the power to create the entities.
Ar-Rahman: The One who has plenty of mercy for the believers and the blasphemers in this world and especially for the believers in the hereafter.
Ar-Rahim: The One who has plenty of mercy for the believers.
Al-Malik: The One with the complete Dominion, the One Whose Dominion is clear from imperfection.