Only the greatest UNSC soldier of all time! He's been in every Halo game except 4 and is known for his Australian accent. There's even a canon error involving Chipps given that he is on Delta Halo during Halo 2 and in New Mombasa during Halo ODST even though they happen at the same time. I don't know if he has a specific in universe backstory, but I have had the honor of listening to his quips during the game.