Answer: Thorin is the current king of the Dwarves.
The previous kings from Lord of the Rings are: Aragron & Sauron
Explanation: Thorin is the leader of the Company of Dwarves who aim to reclaim the Lonely Mountain from Smaug the dragon.
Aragron: He is the long-lost is heir to Gondor and has a kingly lineage stretching back for thousands of years into the mythic past of Middle-earth. He is almost a mythic figure himself, bringing hope to desperate allies and calling upon the ancient spirits of the dead to rally to his banner and fight for his cause. His coronation marks the pinnacle of the story, and it is after him that The Return of the King is named, after all. He is fierce against his enemies and gracious to his friends, transitions from battle-hardened warrior to king of a new age of peace, and rules a prosperous realm justly for 122 years. Not bad for a scruffy-looking ranger.
Sauron: He came close to conquering all of Middle-earth multiple times, and his power and terror were unsurpassed by any other king in the story. “But Sauron’s evil!” I hear you say. Yes, something about being a “Dark Lord on his Dark Throne in the land of Mordor where the shadows lie” does not seem like the sunniest job description. Nonetheless, you can’t terrorize all of Middle-earth for several thousand years without being somewhat effective at what you do