The athlete won medals for swimming and wheelchair racing in the 1988, 1992 and 1996 Paralympic Games.
Mr Hallam, who lived in Pontypool, Torfaen, twice won the London Marathon, setting course records.
The wheelchair racer, who had been paralysed below the chest in a motorcycling accident, was already a good swimmer and within a few years he won the 50m breaststroke at the World Disabled Games.
Mr Hallam’s London Marathon victories in record times came in 1985 and 1987, while he won medals in Paralympics in Seoul, Barcelona and Atlanta.
In 1986 he completed a 400-mile wheelchair ride around Wales to raise money for a centre for the disabled at Cardiff Metropolitan University.
Mr Hallam, who was in his late 40s, retired from competitive sport in 1996.
The athlete, who had been ill for some time, died on Friday, Disability Sport Wales said.
Jim Munkley, Disability Sport Wales board member and fellow British team member with Mr Hallam at the Seoul, Barcelona and Atlanta Games, said: “Chris will be remembered as a true legend of paralympic and Welsh sport.
“Not only was he was true competitor in every sense of the word, but he was also a great character to be around and to have known.
“Disability sport in Wales owes much to Chris and I have no doubt that we would not be where we are today without the huge contribution that he made to the development of our sport.”
John Harris, a lifelong friend and fellow athlete, added: “Quite simply, Chris was my hero.
“For me, Chris was the first of the true professionals in paralympic sport.
“He was the consummate athlete who prepared for every event down to the smallest detail.
“He was a larger-than-life character that you just wanted to be near to.
“’Shades’, as he was known, was a dear friend and will be sorely missed by everyone who ever knew him.
“My heart goes out to his family at this sad time.”