He reckons he's the only person in Scotland to reach the milestone of running the races which are often double the length of a traditional marathon or more.
He said: "There's not that many who can say they've done that. I haven't heard of anyone in Scotland who's done 100 ultras.
"A few people had asked me where I would do my 100th, including a few English organisers, but I'm glad that this one was it. I wanted the 100th to be in Scotland."
Ray, 58, from Darnley, has been selling the Evening Times outside Marks & Spencer on Sauchiehall Street for eight years.
He reached the milestone last weekend, when he completed the Hoka Highland Fling Ultra, running the 53 miles from Milngavie to Tyndrum along the West Highland Way in 15 hours.
He said: "I've been doing them for the past six years but it was more pointed this year.
"There was more pressure on me and it was playing on my mind the whole race.
"It was psychological, I think, which affected me more than just the normal wear and tear."
The run, he said, was the culmination of his running career and gave him mixed feelings.
He said: "Obviously, I felt relieved and happy but in a way it's the end of an era. "Like every project of mine, when it comes to an end it's a funny feeling.
"It's a relief I was able to do it. I didn't want anything to go wrong. All it would take is one stumble and you'd be injured and I didn't want that."
When he started running in 1984 Ray began with shorter distances to raise cash for Yorkhill Sick Children's Hospital.
He's now raised more than £30,000 for various charities, including the Evening Times' Magic Million appeal to help equip a new intensive care unit for Yorkhill.
In 1988 he finished his first half-marathon, the Great Scottish Run, and went on to complete it 13 times.
He ran his first full marathon in Dublin in 1995 and by 2001 had completed his 100th in Le Mans, France, around the famous race track. After that, the challenge was to hit the same mark for ultra marathons.
To acknowledge the achievement, Ray's running number on his electronic checkpoint bracelet on his final race was 100.
Race organiser John Duncan was also on hand to congratulate the runner after he crossed the finish line.
RAY was then honoured at the post-race ceilidh and given a celebratory cake complete with a mini-model of himself.
He said: "It had running shorts and cap and everything. It was sitting down though, which is what I was feeling like afterwards. It looked just like me."
Ray has his own group of admirers, with a Facebook fan club dedicated to him, calling him "one of the UK's most prolific ultra runners".
Despite Ray's admission that he's not giving up running any time soon, he does think he'll be moving to smaller races.
He said: "I did 20 ultras last year. That's like one just over every fortnight. I'll never do that again. I won't be doing very many besides the ones in Scotland now, for financial reasons.
"I really enjoy these terrains anyway – the hills as opposed to the road – and I might go back to do some shorter distances. I'm not finished yet."
AN ultramarathon, also called an ultra distance, is any running event which involves a distance longer than a traditional marathon, which is 26.2188 miles or 42.195 kilometres.
These high-endurance events can take two forms, those that cover a set distance or those that take place over a set time, with the winner covering the most distance in that time.
Common distances are usually 31, 50, 60 or even 100 miles, and common timed events cover six, 12 and 24 hours to three, six or 10 days.
There are 24 ultra marathons taking place around Scotland in 2012 including the JOGLE Ultra, which takes place from John O'Groats in the north to Lands' End in the south of England, which takes place over 16 days and is 860 miles.
Another growing trend is barefoot ultra running, which is running an ultra marathon without wearing any shoes.