In most stories, the main character is a kind and caring individual who stays on the path of good no matter what hardships he or she has to endure along the way, but there are instances where a story works better with a villainous character
In this list take a look at top 5 protagonist who are actually the villain 

5. Nana Hiiragi  

(TALENTLESS NANA)


Nana Hiiragi is the villainous-turned-anti-heroic protagonist of the psychological thriller and horror manga and anime series Talentless Nana. She is sent as an assassin/spy to kill those who possess special ability which might poses threat to human population.




4. Alucard  

(HELLSING ULTIMATE)


He is considered to be an anti-hero. He is a vampire hunter due to being the servant of the Hellsing family and has been modified to stand against his own kind. Alucard is a remorseless and pitiless vampire who has no qualms about being a monster and taking lives of innocents.




3. Lelouch Lamperouge  

(CODE GEASS)


manipulating his own army and committing mass murder of Britannians and Japanese alike, to achieve his goal. Despite being the protagonist, and despite his noble intentions, Lelouch faces many moral challenges that gradually turns him into a villainous character




2. Light Yagami  

(DEATH NOTE)


Light Yagami is the villain protagonist of the Death Note anime series, he was a student when he founded the Death Note. A mysterious notebook that would kill anyone whose name was written in it. Which he uses to eliminate all evil and ends up being a serial killer himself 




1. Eren Yeager (AOT)


From seasons 1–3 he was a clear protagonist However, over the years, he became an antagonist, being the final enemy that many other main characters—including his friends—would fight against.