Blackbeard is luffy without any moral but there are so many things we still don't know about blackbeard. He is scared of death he likes power, and he has committed so many crimes too. But he's more complex t that. han
Dio
Dio is one of the most evil villains and the main villain of Jojo's series. He's kinda psycho he loves suppressing others. But his past is also bad he has committed so many crimes and done bad things. His personality is so complex.
Meruem
Meruen from Hunter x Hunter is another evil and complex villain. He wants to learn about humanity. He just wants to become more and more powerful so that no one can beat him. He's already so powerful but got beaten.
Twice
Twice from my hero academia is another villain followed by a tragedy. He can create multiple clones of himself when he can't tell if he is the original version. He becomes insane because of that. He's a very sympathetic character but complex.
Suguru Geto
Suguru Geto is one of the good guys but he faced so many tragedies that he became a villain. The idea of protecting the whole world became so much that he started doing evil things. But his personality what makes him a complex villain.
Sosuke Aizen
Sosuke Aizen is one of the best villains of all time. With his brain and strategies, he almost destroyed the soul society. But his true motivations aren't clear yet. He is powerful and complex at the same time.
Askeladd
Askeladd is another complex villain because of his actions. Sometimes he did good and sometimes bad. We can't predict his next move at all. Maybe his past is filled with blood and butchery that's why he's like that.
Nagato Pain
Nagato is one of the best villains in the Naruto series. His past is so traumatising and sad you'll instantly connect with him. But his idea of making is dangerous and complex that he can do anything to complete it.