Terrific Trailblazer Thalfi/Thjalfi

The ancient hero known alternatively as Thalfi and Thjalfi was but a normal man of ancient Earth-S gifted with extraordinary speed. Not much has been revealed of him other than his aiding Norse men of his age, although in the modern era of the 20th century he would be called upon time and again by ally Kid Eternity through the lad's time travel abilities to assist him on cases. 

During the latest known adventure, Thjalfi aided Mary Marvel versus an adversary of hers known as Darkling, freeing her from the crippling shadow powers she manifested. In this way, Thalfi was the polar opposite of his counterparts on Earths One and Two in the sinister speedsters known as Reverse-Flash and Rival, who menaced Kid's counterpart the Flash on multiple occasions.

While Professor Eobard Thawne and Professor Edward Clariss used their super-science to mimic the mastery of motion manifested by Barry Allen and Jay Garrick, respectively, Thjalfi worked alongside Kid Eternity and his alter ego of Mercury to combat evil.