What attempts do you know of where man was given gospels outside of scripture?

Galatians 1:6-8 NKJV

6 I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel:

7 Which is not another; but there be some that trouble you, and would pervert the gospel of Christ.

8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.

God makes a special point to warn us here. God wanted us to be aware of any attempts made by man or angels to change what he has given us. So, do you know of any attempts in the past to lead man astray?