At the MCG on Wednesday night the diminutive front-rower will be gunning for his third consecutive State of Origin series win, with the full faith of his teammates that he will do the job as he's always done, despite taking on the likes of giant NSW prop Payne Haas.
Cotter stands at just 180cm and weighs in at 95kg. Compare that to some of the Maroons great props like Petero Civoniceva (193cm, 116kg) and Tino Fa'asuamaleaui (197cm, 107kg) and it is clear Cotter is no man mountain.
"Reuben being so small doesn't matter because he has a big heart and big ticker and keeps going all day," Maroons No.6 Tom Dearden said of his fellow North Queensland  co-captain.
"He is just one of those players you know is never going to let you down. He keeps moving. He competes. He makes his tackles. He is always there. He is a great player to play with."
Reuben Cotter warms up prior to Maroons training at Sanctuary Cove. (Dave Hunt/AAP PHOTOS)
It is why the 25-year-old is one of the first picked for the Maroons.
So how does he feel about his stature?
"I was always pretty average in size compared to everyone else (as a junior). As we left high school, everyone kept growing but I don't think size matters too much anymore," Cotter said.
"The way the game has gone and how fast is it, you can use it to your advantage. You still need to get physical."
Cotter said the key to Origin success for him was between his ears and within his heart.
"I just think it's you not letting yourself down and your teammates down," he said.
"When you are given an opportunity to wear this Maroon jersey, there is so much expectation and that has a massive part to play in it.
"You don't want to let your family down and you don't want to let the five and a half million Queenslanders down. Throwing yourself into it is the best way to do it I reckon."
Cotter played every minute of last year's series, his first full campaign after injury limited him to a sole 2022 showing.
He walked away with the Wally Lewis Medal for player of the series, amassing 135 tackles and 328 run metres across three games.
He will wrangle with giant 194cm and 119kg NSW prop Haas with no fear.
"I take it as a challenge. I am not the biggest bloke but I will try my heart out," Cotter said.
