The poster boy for Fastest Known Times is Kílian Jornet Burgada.
As I post, Kilian holds the fastest known time for the ascent and descent of Matterhorn, Mont Blanc, Denali and perhaps Everest.
But it’s Buzz Burrell who really popularized the concept, co-founding fastestknowntime.com with Peter Bakwin and Jeff Schuler.

Those three run the site on a voluntary basis. And it’s a ton of work.
Buzz himself had been racing routes for decades. He set the FKT on the Colorado Trail in 1999. The FKT on John Muir in 2000.
This interview with Buzz will fill you with respect. Buzz co-hosts his own audio show called the FKT Podcast.