There are no shortages of evil figures in the Harry Potter universe, with the likes of Voldemort and Grindelwald mingling among many other dark witches and wizards. Things like Horcruxes aren't only related to Voldemort, as their roots go far back before Voldemort was even born. The Wizarding World actually has an extremely dark and violent history that precedes the main chronology, and it's interesting to follow the timeline of these events.
These events begin before Hogwarts was constructed and lead all the way up to Voldemort's defeat to give a clear picture of the darkest periods in wizarding history.
Before 100 AD: Herpo the Foul Creates The First Basilisk And HorcruxPhoto: Harry Potter and the Chamber of Secrets / Warner Bros. Pictures
9th Century: The Dark Wizard Godelot Advances The Study Of Dark Magic - And Is Slain By His SonPhoto: Harry Potter and the Deathly Hallows - Part 1 / Warner Bros. Pictures
11th Century: The Bloody Baron Murders Helena RavenclawPhoto: Harry Potter and the Deathly Hallows - Part 2 / Warner Bros. Pictures
14th Century: Witch BurningsPhoto: Harry Potter and the Half-Blood Prince / Warner Bros. Pictures
15th Century: Ekrizdis Creates AzkabanPhoto: Harry Potter and the Order of the Phoenix / Warner Bros. Pictures
1717: Three Dark Curses Are Deemed Unforgivable By The Ministry Of MagicPhoto: Harry Potter and the Deathly Hallows - Part 2 / Warner Bros. Pictures