Okay, “infamous” and “notorious” are opposites of “famous”. Now, the word “celebrity” is related to the word “celebrate”. What I’m looking for is a word to describe someone who is well known, like a celebrity, but isn’t exactly celebrated. Example: John Lennon was a celebrity, Charles Manson is a [need a word here meaning the opposite of celebrity]. I don’t think “notoriety” really fits.
Can anyone come up with something? 
Perhaps what you’re looking for is a noun form of the adjectives “infamous” or “notorious”?
Charles Manson is famously malevolent.
He’s more than famous, he’s infamous!
Maybe “pariah”?
Would you say that he has a plethora of pinatas?
bogeyman
reprobate
wrongdoer
evildoer
miscreant
Notorious and infamous are not opposites of famous. They both mean famous, but only for performing bad deeds.
revilebrity?
antihero?
You are looking for “notorious” without realizing it.
No, he’s not looking for “notorious”. That’s an adjective; he’s looking for a noun. You wouldn’t say that Charles Manson and John Wayne Gacy are notoriouses.
It does in British English
no·to·ri·e·ty
[noh-tuh-rahy-i-tee] Show IPA
noun, plural no·to·ri·e·ties.
How about desperado? Malefactor? Ne’er-do-well?
So, you’d say, “Saddam Hussein was a notoriety.”?
As Wheatcat points out, “notorious” and “infamous” are not opposites of “famous”. The opposite of “famous” is “unknown”.
A “celebrity”, as far as I can see, is somebody who has become famous for no obvious reason, or no reason of substance. Kim Kardashian is a celebrity; Martin Luther King was not.
The opposite of a “celebrity”, then, would be a person who was famous for something truly deserving of notice (which could be something very good, or something very bad). I’m not sure if there is a word for that.
I think the above-mentioned neologism “malebrity” is your best option.
I’ve never heard it, just to add one British data point.
Yes. Here’s a few examples:
http://books.google.co.uk/books?id=8UqLC55IQVkC&lpg=PA119&ots=1fIDpNEVzh&dq=“was%20a%20notoriety”&pg=PA119#v=onepage&q=“was%20a%20notoriety”&f=false
“*Dammer was a notoriety at Washington parties”
*
http://jacketmagazine.com/17/ern-thom.html
*Max, as a dynamic, outspoken, extravagant, very intelligent, quick, witty and bright young man, obviously was a notoriety in Adelaide, within his own field, and I think had undoubtedly made many enemies, and I think they were only too happy to seize on this chance to get one back on him.
*
Ajay Devgan is a notoriety in the Indian sub continent
https://archive.org/stream/OldGodsFalling/TXT/00000075.txt
*In England, he was a notoriety no longer amusing, but
rather to be avoided. *
The first one is American, the second presumably Australian (can’t get it to open), the third Indian and the last I can’t get to open.