Ex-Wales rugby international Richard Parks has conquered Everest as part of his challenge to climb the world's seven highest peaks and both Poles.
Parks, 33, has now scaled five of the highest summits and the poles as part of his record-breaking quest.
His climbing partner, double Olympic gold medallist rower Steve Williams, has also reached the summit, Parks's 737 Challenge website says.
Parks also aims to raise £1m for a cancer charity.
Parks, the former Newport Gwent Dragons player, and Williams, had to abandon their first attempt at the final climb to the summit of Everest because of high winds.
Speaking from the summit, Parks said: "It's hard to really put this in to words, it's just the most amazing feeling.
"There's just the most amazing mountains, clouds as far as the eye can see, one way's Nepal, the other Tibet. So many times I didn't think I was going to make it.
"You know, we have been blessed, we sat yesterday in really high winds in camp four, our tents absolutely rattling, I was really worried that we might not get the shot, we might not get the opportunity.
"Our Sherpas Sirdar and Mingma have been absolutely amazing and we just held our nerve. It's brutally cold, the winds are pretty low and there is not a cloud in the sky on the summit. It is just amazing."
He described the support he had received for the challenge, which is in aid of Marie Curie Cancer Care, as "amazing".
Parks started his challenge last December and has set himself seven months to complete it.
A shoulder injury forced his retirement from professional rugby in May 2009.
During his career he earned four Welsh caps, and played for Newport Gwent Dragons, Pontypridd, Celtic Warriors, Leeds and Perpignan.
BBC Wales
Immense effort from Richard. Congratulations and all the best for the last few challenges.
