Here are some options:
Based on fame and renown:
* Obscure: This emphasizes a lack of widespread recognition.
* Unremarkable: This suggests the person or thing is ordinary and not worthy of note.
* Forgotten: This highlights the absence of memory or remembrance.
Based on accomplishment and impact:
* Mediocre: This emphasizes a lack of excellence or distinction.
* Insignificant: This suggests the person or thing had little impact or importance.
* Trivial: This implies the person or thing was unimportant and easily dismissed.
Based on being exceptional:
* Average: This suggests the person or thing is typical and unremarkable.
* Ordinary: This emphasizes the lack of anything extraordinary or unique.
* Common: This signifies the person or thing is widespread and not exceptional.
Ultimately, the best opposite depends on the specific context in which you're using the word "legendary."