Friendship is a powerful theme in the world of anime - but that doesn't mean that every anime character is actually good at the whole friendship thing. In fact, there is an abundance of abysmally bad anime friends who deserve to be taken to task for their terrible behavior.
Who are the worst anime friends? Some of them have done such dramatically awful things that there's no possible way they can ever make up for them. Griffith from Berserk is a great example - he dramatically betrayed his friends by sacrificing most of them in exchange for god-like power. Other terrible anime friends may not have committed crimes against humanity, but are still guilty of interpersonal cruelty. Eriri Spencer Sawamura of Saekano: How To Raise A Boring Girlfriend might not have taken Tomoya Aki's life, but she sure did betray him by abandoning their friendship to preserve her reputation, then blamed him for causing her pain.
No matter what precisely they're guilty of, these anime friends are truly the worst.