Some great nominations here. As I'm partial to snow sports, (at least when I was younger, I've retired to the desert), here's some new names for the list:
From my perspective World Cup Nordic skiers are some of the best athletes in the world, and within that group Norwegian Therese Johaug is in a class by herself in distance events. If you ever want to destroy yourself in no time at all, go out and skate ski (freestyle) a few Kilos.
From an alpine discipline, Czech Ester Ledecka's 2 gold medals in the same Olympics in 2 different sports, (skiing/snowboarding), is for me one the most amazing performances I've ever seen. Better yet, she's remains at the top of both sports. Once you get past "sliding down a snow-covered hill on plank/s", there really isn't a great deal of crossover between the 2. Following her on social media she posts vids windsurfing, waterskiing, even swinging a tennis racket and she seems to be quite expert at all.