Winner: Snape The kind of versatility in magical abilities that Snape displayed was almost around the level of Albus Dumbledore and Voldemort, making him easily more powerful than the average wizard and even the members of the Order of the Phoenix and the Death Eaters.
There wasn't much said about Nymphadora Tonks in the original series or movies, but there is enough known about her to suggest she could defeat Bellatrix Lestrange in a fight. Tonks was one of the youngest people to ever become an Auror. She also had the extra advantage of a being a Metamorphmagus.
Additionally, Snape is more skilled in potions than Dumbledore, making him a powerful contender for Albus's spot on the list. Albus, however, edges out Snape thanks to the former's greater base power, and deeper understanding of the complexities of “old” magic.
Bellatrix didn't trust him. Nor did she like him. She likely acknowledged his magical ability, but nothing beyond that. Atop her list of grievances is the fact that he'd held a cushy job teaching at Hogwarts while she and other loyal Death Eaters wasted away in Azkaban, suffering for what they believed in.
Verdict: Snape Is the Stronger Wizard
McGonagall is surprisingly skilled in the Dark Arts but not on the same level as Snape. She's also most likely incapable of casting the Killing Curse, which puts her at a disadvantage.
Lord Voldemort is one of the most feared and powerful wizards. He is known for his cunning and ruthlessness. Formerly known as Tom Marvolo Riddle, Lord Voldemort was the most formidable evil wizard in the entire universe.
Lord Voldemort (Ralph Fiennes), aka Tom Riddle, was described by Dumbledore as one of the best students ever to graduate Hogwarts as well as "the most dangerous Dark wizard of all time." Before he had even learned about the existence of the Wizarding world, he was terrorizing his fellow orphans with impressive but ...
Bellatrix had a fear of rejection as well where Voldemort was concerned, wanting nothing more than to please him but was always frightened that she would lose his favor.
Cruciatus Curse ('Crucio')
Harry tried to use this spell himself. The first time was against Bellatrix after she had killed Sirius. His attempt was unsuccessful because, as Bellatrix mockingly explained: 'You need to really want to cause pain – to enjoy it – righteous anger won't hurt me for long…'
His reaction to Bella's death was akin to his reaction at the loss of the Cup, which was when he realised that his own immortality was jeopardised amidst war and his own death could have been near.
During his school days and shortly thereafter, he probably hated James the most. He seemed to be the ringleader bully, then married Lily.
The Head of Slytherin is Horace Slughorn (who left the role to Severus Snape for fifteen years before taking it up again in 1996) and the House's patron ghost is the Bloody Baron.
Bellatrix Lestrange was Lord Voldemort's equal in cruelty, if not worse than him. She was unparalleled when it came up to committing some of the most horrible acts of cruelty and destruction. She truly belonged to the Dark side and loved to embrace it.
No matter his rage and grief, Harry doesn't have what it takes to defeat Bellatrix. Bellatrix is Voldemort's most loyal and most powerful Death Eater of all, and she claimed many victims in Voldemort's name.
She married Rodolphus Lestrange after leaving Hogwarts "because it was expected of her" to marry a pure-blood. However, Rowling stated in an interview that Bellatrix truly loved Voldemort.
Avada Kedavra, also known as the Killing Curse, kills a person instantaneously and without injury. There is few counter for it, and only one person, Harry Potter, has ever survived it with Sacrificial Protection that has been endowed upon Harry Potter by His Mother Love for Him.
Unlike many Death Eaters, when Bellatrix was imprisoned in Azkaban, she did not lie about her loyalty, instead proudly declaring herself to be a follower of Voldemort. Even Voldemort himself had a considerable amount of respect for Bellatrix.
She seemed to have a sick obsession with Voldemort that went so far beyond romantic desire. She was also very clearly scared of him and his remarkable magical abilities. However, the reason for her obsession clearly went a lot deeper and probably had to do with the relationship that she had with her parents.
5 Bellatrix Lestrange: The Cruciatus Curse.
Her greatest fear was probably failure.
Voldemort's greatest fear is death and as a result a boggart takes the form of his own corpse. It is unsurprising that this is Voldemort's biggest fear. After all, he did split his soul up encasing it in various horcruxes just so to keep himself from dying.
Dumbledore may have been a legendary wizard, but he can't be compared to, well, Merlin, a wizard so legendary even Muggles know of his exploits. Merlin was the world's most famous wizard, and, arguably, the world's most powerful.
1. Albus Dumbledore. Image via Warner Bros.
The Killing Curse was created in the early Middle Ages by Dark witches and wizards. Primarily, the curse was used to quickly slay opponents during a duel.