Tyson

Tyson is a cyclops that looks like he has two eyes to Percy Jackson because of The Mist. Tyson plays many roles in all the books.

Role in "The Lightning Thief"
Tyson is not mentioned in this book.

Role in "The Sea of Monsters"
Tyson deflects firey celestial bronze dodgeballs in the mishaps at Merriweather Prep. Tyson also tries to fix the engine on the CSS Bermingham when it explodes, but he still lives because the Hippocampi saved him. At the end, Tyson is summuned to the Cyclops Forges in Poisedon's underwater palace.

Role in "The Titan's Curse"
As far as i've read, he has only been mentioned in an Iris Message.

Role in "The Battle of Labyrinth"
To be found out.