Is famous a prefix or suffix?

"Famous" is neither a prefix nor a suffix. It is a root word on its own.

* Prefixes are added to the beginning of a word (e.g., "un-" in "unhappy").

* Suffixes are added to the end of a word (e.g., "-ing" in "running").

"Famous" can be used as a base word to create new words with prefixes and suffixes, such as "infamous" or "famously".