What is Harry Potter's enemy's real name?

There are several enemies but the main ones are

Voldemort- He killed Harry Potter's parents

Bellatrix Lestrange- Tortured Frank and Alice Longbottom for information on Voldermorts death

Barty Crouch Jr- He was involved in a plot to return Voldermort to power and participated in the torture of Frank and Alice Longbottom along side Bellatrix

Gellert Grindelwald- Dark wizard who tortured Muggles (non-magical people) a 100 years before Harry Potter was born

If you read the books or watch the films you will see more detail and learn the names of more villains