Contenders for "Greatest":
* Albus Dumbledore: Widely considered the most powerful wizard of his time, known for his knowledge, wisdom, and strategic brilliance. He defeated Grindelwald, the only other wizard who could match his power.
* Merlin: A legendary wizard, considered by many to be the greatest of all time. His accomplishments include founding the Order of Merlin and inventing powerful magic, although his story is mostly told through myths and legends.
* Gellert Grindelwald: While evil, Grindelwald was undeniably powerful, capable of challenging Dumbledore and almost achieving world domination. His ambition and magical skill are undeniable.
* Lord Voldemort: Voldemort is arguably the most feared wizard of his era. He is incredibly powerful, has mastered dark arts and has a unique understanding of the Deathly Hallows. However, his obsession with power and his lack of love ultimately led to his downfall.
Factors to Consider:
* Power: Raw magical strength and the ability to perform complex and powerful spells.
* Wisdom and Knowledge: Understanding of magic, strategy, and the ability to use magic for good.
* Moral Compass: Whether they use their power for good or for selfish gain.
* Impact on the World: Their contributions to the wizarding world, whether positive or negative.
Ultimately, the "greatest" wizard is a matter of personal opinion. There are many great wizards in the Harry Potter universe, each with their own unique strengths and weaknesses.
It's worth noting that the story isn't solely about power. It's about the choices we make and the consequences of our actions. Even the most powerful wizards can be undone by their own flaws.