An FKT Setter is a hiker or trail-runner who has at any point set the record for the "Fastest Known Time" of a specific trail or route. They may not hold the current record or FKT, but have at one point held the record.
Types of FKTs
There are multiple recognized types of FKTs, including Unsupported, Supported, Women's supported, and Women's Supported. An unsupported FKT is one in which the hiker does not receive outside help such as food drops or resupplies by any outside party, and relies on only themself to complete the hike or run. These times end up being significantly longer than Supported FKTs. Often times entire teams of people will set up caches or sleeping stations for the hiker in order to help them achieve the lowest time possible.
Resources
The highest regarded source for FKTs is fastestknowntime.com. Here there is a wealth of information regarding the sport, and records are updated very frequently.