Nemeses

The farmer's nemeses were the locusts that ate his crops year after year.

The scientist believed that time was the ultimate nemeses, always ticking away and limiting his ability to achieve his goals.

The hero and villain in the action movie were nemeses.

His stubbornness was one of his nemeses that often led to arguments with his loved ones.

Writer's block and self-doubt were his nemeses when it came to writing.