Human, then Beheaded Kamikaze
Brett Sanderson is a character that appeared in Serious Sam 3: BFE promotional material and is a multiplayer character in Serious Sam 3: BFE.
Brett Sanderson is a headless man in a blue sweater and has black gloves on. He decided to volunteer to be a Beheaded Kamikaze after reading about it, because he wanted a lot more excitement in his life, and nothing is more exciting than running around without a head with bombs in your hands. After trying out for the role in a studio, he was selected as a Beheaded Kamikaze and promptly beheaded as soon as he was told he was qualified to be one. He was then given a bomb in each hand, and enjoyed life for a while by doing things like playing baseball with his kids and visiting Mount Rushmore. Eventually, he charged towards Serious Sam in The Last Man on Earth. Unfortunately for him, Sam killed him, ending his life in a bloody mess. However, he now serves as an inspiration for Beheaded Kamikazes across the world. RIP Brett Sanderson.
He also appears as a multiplayer character that can be selected by the player. Why he's fighting against Mental is unknown, as he was pretty excited about being a Beheaded Kamikaze in the first place.