Yiannis Tridimas (born 22 February 1945, in Andros, Greece) is a long-distance fell runner, noted as being the only 60-year-old to have completed an extended version of the Bob Graham Round, covering 60 peaks in under 24 hours.

He has completed a solo run between Snowdon and Pumlumon in Wales, taking in all the major hills in between.

[4] In 2003 Yiannis, along with teammate Ray Baines were winners in the veteran section of the Long score class, at the Karrimor International Mountain Marathon (KIMM).

In the photo below Yiannis is seen with Ranulph Fiennes at the start of the 2004 Lowe Alpine Mountain Marathon where they finished in tenth place in the Elite class.

[6] Yiannis, now a preeminent figure in the world of fell running has been a guest speaker at fell running award ceremonies[7] and is mentioned in the 2007 Autobiography by Sir Ranulph Fiennes: Mad, Bad and Dangerous To Know.