The Wizard was a human male who was very adept at using magic. He was the father of Rose and Velvet, though he never acted as such. He also is the grandfather of the Fourth Overlord (The Overlad). He is the Second Overlord's body replacement.
He is said to have constantly trotted the globe seeking to root out evil wherever it dwelt. He assembled a group of heroes, each with their own unique traits, to defeat his possible arch-nemesis the so-called "Second Overlord".
Although they succeed with the help of an unexpected ally — the 8th hero who simply turned up on their travels and apparently showed desires to aid them (eventually becoming the next Overlord). The task cost the Wizard his body as he was attempting to examine the old Overlord's corpse for any signs of life, the almost dead Overlord's spirit emerged from the corpse and possessed the Wizard, "overwriting" his soul.
The Second Overlord used the Wizard's body to corrupt the remaining heroes.
It should be mentioned that the Wizard is seen before the final act in the Golden Hills where the dwarves have gathered in an establishment similar to a pub. He crosses over the walkway as a cinematic showing the area plays.
After the Overlord kills the heroes (excluding Jewel, who was instead imprisoned) he returns to the Dark Tower and attempts to overthrow the Overlord. However Rose or Velvet manages to damage the Tower Heart and the Wizard (the Second Overlord, actually) loses control over the Overlord's minions. During the final battle, he fights the Overlord with his own army of minions and the ability to summon tornadoes. He is then killed by the Overlord.
Personality and Traits Edit
The Wizard was not a very fatherly man, as Rose mentioned about how he was never at home when they were young which led to the Wizard's wife spoiling Velvet. He was also obsessed with wiping out evil, in the end paying a hefty price.
The lines he mutters as the player faces him in the final battle sequence clearly present how he corrupted other heroes.
"Have another roast pig Melvin...have two...you're a Hero now."
"Have a rest Oberon, heroes need their rest"
"I think she likes you Sir William, if you want to slip away with her, I won't tell anyone."
"Goldo you can have all the gold you've ever wanted, my friend! No one would refuse a hero."
"That Jewel had everything, it turned out what she wanted was what other people had."
"Hard to see what you love taken away, isn't it Khan? When reason is gone, nothing is left but madness!"
He corrupted the 8th hero/Third Overlord with the sin of Pride, making him believe that he was the supreme ruler of the Dark Tower (and eventually Spree and Heaven's Peak) when in fact he had never been more than a tag-along.
Or so he thought. What he didn't realized is that the sin of Pride had instead corrupted him, evidenced by his constant rambling about how he tricked and manipulated all the Heroes, telling the Third Overlord about his cunning plan, and taking great "pride" in his work.
Also, it is unlikely that the 8th Hero/Third Overlord actually believed he himself defeated the Overlord. Since Gnarl did tell him that the Heroes raided the Tower after they killed off his "predecessor". So it is more likely that the Third Overlord has amnesia after falling off the Dark Tower, and simply taking Gnarl's words to be true that he is the next in line (may as well take the offered job when you don't even know who you are to return to, right?).
Behind the Scenes Edit
It is possible that the Overlord doesn't have complete control over the wizard's body, because of him referring to Velvet and Rose as if he knew them personally before. Probably he's influenced by the Original Wizard's soul having some kind of control, but overwhelmed by the second Overlord's corruption. Also by the fact that he can use spells not related to an Overlord (via Tower Objects) such as Tornado and Levitation, proof that those spells possibly belong to the Wizard and that the Second Overlord has taken his memory as well. Also noticeably the tower's background has become darker when he returns likely because of the wizard overwriting the corruption of the tower to his evil energy type. Although this section of the story could take place during the night.