American English, native speaker here. I've always used "crept". In your question did you mean to say that "creeped" seems to be used rarely ( not a lot ) by native speakers? "commonly" means that someone uses the word often.

The one that is grammatically correct is "Crept" "Creeped" would only be used in a friendly conversation or used for personal use.

Hi Marison, I understood well. ^^ "freaked me out" seems easier to use for me! Thank you for the details and the useful link!!

Hi Yumiko! We use both in English. Since both sound awkward, we would probably avoid using either, but on a daily basis, "creeped" is more often used. For example, if a girl is out with her friends, she might say, "Ew. That guy really creeped me out. I don't like him." The meaning here is synonymous to "weird out". "Crept" would likely be used in formal writing, such as in essays or newspapers. It would be synonymous to "snuck up" (past tense of "sneak up on") in most cases. Here is a site for examples: http://grammarist.com/usage/creeped-crept/

Thank you guys for your comment!