Rugby league lost one of its toughest and most colourful figures after legendary player and commentator Rex Mossop died aged 83 on Friday after a long fight with Alzheimer's disease.

Mossop, a dual-international, who switched to league after playing eight rugby union Tests for the Wallabies, was a fierce competitor whose tough-as-nails attitude earned Manly's forward packs of the 1950s and '60s a feared reputation.

Mossop's enormous frame made him a target on the field, but his remarkable talent saw him transfer his skills from rugby union into the 13-man game with ease.

He went on to play 129 games for his beloved Sea Eagles, with whom he was a life member, including grand finals in 1957 and 1959.

After his playing career, which also included 12 Tests for the Kangaroos, Mossop was a key figure as rugby league evolved into the televised sport it is today in his role as a controversial commentator for more than three decades.

Manly confirmed on Saturday they would wear black armbands and hold a minute's silence in memory of Mossop before Monday night's NRL clash with traditional rivals Parramatta.

Former Manly hooker Max Krilich's earliest memories of Mossop were on the sidelines of Brookvale Oval as a ballboy, while watching the giant second-rower thumping opponents, and invariably being sent from the field.

"I was about eight or nine. I remember running up and down the sideline watching this very, very tough man playing a very physical game of football who wanted to fight everybody," Krilich told AAP.

"That was Rex Mossop, and obviously he got sent off a fair bit over the years with that style. He was an uncompromising person who really played it tough."

Later, Krilich would learn first hand just what it was like to play against Mossop - and exactly why the man known as "Moose" had such a devastating reputation.

"We used to play touch football down at Brookvale Oval when I was 15 or 16, and he coathangered me one day - in touch footy," Krilich added.

"He said 'son, if you're going to play grade football later on, you've got to learn to cop that'. I went home crying!"

Tributes flowed on Saturday for Mossop's contribution as a player and as a commentator, with the modern-day voice of rugby league, Ray Warren, describing him as the Frank Sinatra of commentary.

"He did it his way. He was the Frank Sinatra really. 'It was my way or the highway'," Warren said on Triple M's Dead Set Legends.

"He was a magical piece of equipment to have on television because he was controversial."

NRL chief executive David Gallop also acknowledged the influence Mossop had on making rugby league such a television success.

"He wasn't the first man to call rugby league on television, but he was the man who changed it forever," Gallop said.

"He was a giant character in the game.

"He was incredibly tough and talented on the field and not a lot different in the commentary box.

"Rex's sense of showmanship is something that will always be remembered and his contribution to bringing rugby league to television audiences can never be understated.

"Rugby league remains the ultimate television sport and the character of broadcasters like Rex, as they opened the game to new audiences, was a big part of that success."

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