Though not as dramatic as being related to a hero, a villain being the hero's or one of the primary protagonist's former friend is a recurring trait in fiction. This is because the idea of a person the hero trusted as a friend turning on them can often have a great psychological effect on the hero and make them reluctant to fight that person.

Frequently, the friend joins the side of evil because of being brainwashed/possessed so as to be used against the hero, which makes the hero even more reluctant to fight them. These characters can also be On and Off villains, changing between evil and good. In these examples, when the Friend of the Hero is not being an evil villain, he or she can get along well with the hero.

On the flip side, this villain's betrayal or any other evil acts made the hero despise him/her and want nothing more than to kill their old friend.

This can also count for Redeemed villains, who become friends with the heroes they fought after redeeming themselves. Remorseful villains can also count if they still feel friendship towards heroes.

IMPORTANT: this category is only for villains who were (or even still are) genuinely friends with the hero/heroes. Faked friendship for manipulation or other goals is NOT ACCEPTED (e.g. Sir Topham Hatt).

However, even Complete Monsters can qualify if they were once true friends of the heroes (i.e. Shadow Ahriman). Unfortunately, this category CANNOT apply to the Complete Monster in the present as the character does not value a genuine friendship with the hero; thus, this could only apply to the Complete Monster if the said villain was friend of the hero IN THE PAST before they became Complete Monsters. Even if they are a friend of the hero in the present while remaining Complete Monsters, it is merely out of self-interest and is not genuine friendship - therefore these types would not count either.