Is The Godfather based on real life events?

Ever heard of this thing called the Mafia?

It's not based on any person in particular but it is loosely based on Italian mafia life. I'm not sure how they came to know so much about it but it is pretty realistic. Especially the film Goodfellas. However, by the time Goodfellas came out, people had a greater understanding of how organized crime worked. When The Godfather came out, there was still quite a bit about OC that people didn't know about.

But no, it's not based on real events.

Yes. Lots of the characters are based on actual people or a combination. Johnny Fontaine is based on Sinatra. Margot is Ava Gardner. Moe Greene is Bugsy. Joey Zasa is Gotti. Woltz was Cohn. Just an fyi. The horse head scene was real. Vito was based on frank costello. Lots of the stories are similar. Michael at restaurant going to restroom and making the hit and then to Sicily is a lot like Lucky Luciano.