The phrase "bête noire" is commonly used to refer to something or someone that is particularly despised or hated. However, there are many other ways to express this sentiment in English. Synonyms for "bête noire" might include such phrases as "arch-nemesis," "mortal enemy," "rival," "adversary," "foil," and "antagonist." Other possible terms might include "thorn in one's side," "pet peeve," "irksome nuisance," "bothersome bother" or simply "annoyance." Depending on the context, any of these phrases or terms might be an appropriate substitute for "bête noire" in a piece of writing or conversation.