Boyan Petrov
He had climbed 10 out of 14 eight-thousanders, all without supplementary oxygen. This made him the Bulgarian altitude climber with the highest number of successful ascents of peaks over 8000 meters. He was the first Bulgarian to climb four of those mountains - Gasherbrum I (2009), Kangchenjunga (2014), K2 (2014) and Manaslu (2015).