We're going to examine Oliver's Scars & Tattoos.
Determine the chronology of when they happened.
Who gave them to him?
How did he end up with them?.
Oliver Queen arrived in the pilot sporting a litany of scars and tattoos.
Way back in the pilot Oliver having come out of the shower, examines his body in a mirror revealing by my count 15 scars and 3 tattoos that he accumulated in his 5 years away. Oliver arrived on Lian Yu with one single scar on the back of his head, I'm going to attribute that to a bar fight (same reason SA has it, its the only 'real' scar). Oliver also has a plethora of psychological scars that are harder to see.
Lets examine how these were all accumulated and when. Chronologically, starting from when we first landed on Lian Yu.
There are several different people who inflicted Oliver's scars/tattoos. Some larger than others, some more than others. Lets find out.
There is a line in season 3 where Olier describes what his scars were inflicted by, also noting that no grenades caused any.
Before the island Oliver is an entitled brat, lets be honest. He is however predominantly a pristine specimen.
Oliver's got a scar on his left shoulder that I've been unable to identify the source of.
Aboard the Amazo Oliver was shot by the captain to proove his worthiness for Ivo's experiments. Handed a kit to stitch himself and retrieve the bullet as everyone else had, Oliver dutifully repairs himself. Curiously though, without scarring himself.