J.K.Rowling has introduced numerous dark characters throughout the Harry Potter series. These dark characters not only mastered the dark arts but also ruled the dark world. Gellert Grindelwald and Voldemort were the darkest wizards amongst them. These wizards were those who practiced dark arts, dark spells, vanished into dark smoke and indulged in the illegal breeding of dark creatures. These are the most powerful wizards and witches of all times which ruled the dark world.
Tom Riddle who latter was known by the name of Lord Voldemort, was the most powerful wizard after Albus Dumbledore. He had unbeatable magical abilities and skills. He was a parcel mouth, master planner, could read and control minds, performed duel spells with utmost perfection. He was also known as the dark lord, who ripped his soul into Horcruxes in order to attain immortality. He was very cruel, a stone-hearted creature who was dear to none. Harry Potter, the chosen one eventually cracked his secret of immortality and destroyed all the Horcruxes, which lead to the death of the master of death eaters.
He was considered the most dangerous wizards of all time.It was revealed in seventh part that He and Dumbledore were good friends, but he was expelled from the Drumstrang institute for carrying out dark arts. Albus Dumbledore and Gellert Grindelwald do not meet each other again until the famous duel between the two in 1945. Dumbledore defeated Grindelwald and Grindelwald is sent to Nurmengard where he remains for the rest of his life. Grindelwald later stole the elder wand from Mike. He was a very complex figure who wanted to achieve results at any costs. He was extremely talented and dangerous.
Herpo The Foul
He was a wizard which usually appeared on the chocolate frog card. There are not many appearances of this great wizard but this was the most genius wizard of dark arts. He was the first wizard who hatched a basilisk and created a successful Horcrux including the process to do so. He was an amazing inventor who invented many spells and vile curses, which made him gain a huge name in magic word. Due to the creation of Horcrux his soul faced the similar faith as that of Tom riddle and had terrible death.
She was an extremely powerful and a cruel witch.She learned wizardry in Hogwarts and later became a death eater. She was sent to Azkaban for torturing two Aurors. She later escaped in a mass breakout from Azkaban in 1996. She was a brutal killer who killed Sirius Black, Dobby, members of Malfoy family and much more. She was the last witch that was standing with the Voldemort in the last war who killed by Molly Weasley. She was very intelligent, violent, could easily be distracted, was obsessed with pure blood, knew occupancy, dueling perfectly and non-verbal spells. She was a natural leader and her skills complimented with Lord Voldemort.