I am (to my knowledge) not on facebook - so why do I keep getting messages from people I don't know?

To be honest - I am a bit wary of unsolicited messages (you know the usual - King Akimbo from umbongo wants to share his fortune with you etc etc) - and have avoided the 'verify your bank details' ones - but now the latest are people from facebook (allegedly) wanting to get in contact - I just delete them - Is this another phishing scam? - thanks