he was a evil wizard that wants to very powerful
Answer: No. Voldemort was stronger. He was the strongest wizard known to wizard kind aside from Dumbledore. Answer: Most likely, but one couldn't tell for sure, because Slytherin lived a thousand years before Voldemort. (Note: Voldemort was very proud to be Slytherin's Heir.)
Lord Voldemort
Voldemort, obviously.
Albus Dumbledore
No, Lord Voldemort is a human wizard. In the first book he drinks unicorn blood to sustain his life.
Lord Voldemort and his death eaters.
A powerful wand alone does not win a battle. The skill of the wizard is important too, and Voldemort is a wizard on Dumbledore's level of skill and power. Voldemort also has several horcruxes, and he cannot actually die until they are destroyed.
Of course! When Voldemort dies he loses his powers from him (Parseltongue...) but that doesn't mean he isn't a wizard! As I like to say... Once a wizard always a wizard. ;p
The most powerful villain is Lord Voldemort. The most powerful wizard is either Dumbledore or Lord Voldemort. This has not entirely been established; however, it is stated that Dumbledore is "the only one he [Voldemort] feared".
Lord Voldemort or He Who Must Not Be Named
Dobby's sock, unicorn turds, voldemort's nipple, etc.
Voldemort is a dark wizard, who tries to kill and rid the world of all muggleborns(a witch/wizard who was born into a non-magical family) as he thinks that they are a disgrace to the wizarding world. He tries to kill Harry Potter but fails.