Waverider
Matthew Ryder was born in a possible future that was under the control of a super-powered dictator named Monarch. Ryder volunteered for a time-travel experiment and was transformed into living energy tachyons. Traveling back in time, Ryder hoped to find and stop the dictator in the past; however, his presence in the past actually allowed Monarch to exist.
Monarch eventually was defeated in the past, and Waverider devoted himself to preserving the timestream from threats and crises.