Are the assassins creed characters real

It depends on who you mean.

Some of them; like Niccolo Machiavelli, Rodrigo Borgia, Caterina Sforza, Leonardo Da Vinci, etc..etc - are real. But I don't think that Ezio, Altair, Desmond, or Malik, etc..etc, are real.

But, some of the characters are modelled after real people; Lucy Stillman is modelled after actress Kristen Bell.

I hope this answers your question.