We had a huuuuuge rooster when we first started keeping chickens that fought off large dogs on multiple occasions. Unfortunately he fought off the wife and the kids a few times as well, so he had to go.

He got after my 4 year old son once and pecked a hole in his shoulder before I got to him, but when I kicked him it was like kicking a bag of concrete. It hurt my foot enough I was sure I had killed him but he got up and walked off like nothing happened.