Olympic legend Sir Jason Kenny is one of the top names taking part in the event on Saturday, June 8.
The line-up also includes Sevens rugby players Sam Cross and Heather Fisher, Gareth Warburton, hockey player Shona McCallin, and rower Moe Sbihi.
Kenny is the holder of most Olympic gold medals (7) and medals (9) for a British athlete - winning his first gold back in Beijing in 2008.
The quirky Whole Earth Man v Horse marathon sees runners compete against riders on horseback through a mix of road, trail and mountainous terrain.
This year they will complete over more than 24 miles.
The event began in June 1980 and has since become world-renowned.
The horse has won most of the events over the years, although two legs have come up trumps for the past two years.
2022 saw world champion trail runner Ricky Lightfoot win the event - the first human winner since 2007, with the first time in 2004.
A fourth human winner was witnessed last year when Daniel Connolly came out on top of more than 1,200 runners and 60 riders.
Come along to watch the action as the runners leave Llanwrtyd at 11am shortly followed by up to 60 horses and riders.