Barcelona climber Miguel Ángel Pérez Álvarez was found dead in his tent on K2 on Wednesday having reached the summit of the supremely challenging mountain the day before.
The 46-year-old bivouacked a short way below the summit at 8,200 metres (26,900 feet) on Tuesday night before going down to camp four the next morning.
He arrived at the camp "apparently in good condition", fellow climbers told Spanish mountain news website desnivel.com.
However, he was found dead in his tent early on Wednesday afternoon.
At 8,611m K2 is one of the most difficult peaks in the Himalayas, with around one in four climbers attempting the ascent dying in the process.
This makes it the second most deadly eight-thousander in the Himalayas behind the Annapurna massif where nearly one in four people die while climbing.
Pérez Álvarez has previously attempted to summit K2 on July 26th but decided to turn back 300m below the top of the mountain because of the extreme cold.