So I've noticed that there is this on going book series done by Rick Riordan. Well, he actually has many. Percy Jackson, Apollo, and the Lost Hero. And it got me thinking a bit. How much of mentioned monsters, gods, etc. is actually true, or it it just to enhance his story?
So after some researching about the writer, I've got this answer. It turns out that all of the mentioned gods, titans, monsters, and historic heroes are real. That's right. Any name (except from the modern demigods and Camp Halfblood) is taken from real Greek Mythology. But there's a catch. Rick Riordan may have revived or slightly altered some of the monsters or titans. For example, Typhon was trapped under a mountain in Greek Mythology, but he comes back in Percy Jackson. So does Cronus and many other monsters.
So the answer is yes, all of the characters come from the Greek canon, but the things that they do, and the timelines that they exist in aren't part of the historical canon.
I suggest reading Rick Riordan's guide to Greek gods and heroes, as they provide tons of information on true mythological events.