Lion Voltron is a giant robot currently composed of five robot lions (Black, Red, Green, Blue, and Yellow) joined together.
Voltron, Defender of the Universe continuity
Voltron had been defending planet Arus for many years. It is implied (from the narration) that Voltron was instrumental in the founding of the Galaxy Alliance.
During a Doomite attack on planet Arus, the witch Haggar cast a powerful spell splitting Voltron into five Robot Lions. Keith and company made contact with the Castle of Lions and brought Voltron back into service.
Currently, Voltron is operated by the Voltron Lion Force, led by Commander Keith.
Origins
While Voltron must now form from the combining of the five Lions. Voltron was once a mecha, a sentient being of sorts before being separated into five robot Lions.
Weapons
Blazing Sword
Voltron's ultimate weapon. The two hands touch each other and forms a sword. This sword is often used to slay robeasts, often by slicing them in half.
Spinning Laser Blades
Forms a spiky disc which he can throw at an enemy.
Lion Head Attack
Involves two or four of Voltron's appendages to lose their heads and go flying at the enemy.
Lion Torches
Fired from the mouths of the Red and Green Lions.
Sting Ray Missiles
Fired from the mouths of the Blue and Yellow Lions.
Ion Darts
Beams with tiny darts in them which fire from part of the head.
Eye Beams
Shoots destructive rays of energy from the eyes.
Electro-Force Cross
This cross emits from the one on the Arusian seal, which adorns Voltron's chest.