Traceur

Traceur is often defined as a practitioner of parkour. It originally was a name for a member of David Belle's parkour group and later on its meaning was meant to be expanded for anyone who does parkour. When an outsider, like for example a journalist writing an article, wants to talk about parkour, they will often use the word traceur.
The problem is that nowadays this word is used only rarely inside of the parkour community. Using it isn't correct anymore, but that is up to debate.
There is no unifying term for someone who does parkour. Possible terms are: parkour practitionere, freerunner (some would argue this word has a different meaning), parkourist (this word is not taken very seriously), parkour athelet.