Timeshadow was a patient at the U.S. military detoxification center along with Michael Nowlan. Already an adult, unlike most mutants his latent mutant powers did not active during puberty. Instead they they were kicked into gear by a chance encounter with Michael Nowlan during their time at the detox center. When the two men met and shook hands, the energies wielded by Michael Nowlan inadvertently activated the x-gene in Timeshadow. Immediately his mutant powers manifested.
Timeshadow went on to join the Alliance of Evil, a group of mutants terrorists banded together by Apocalypse. Through Timeslip's connection, Nowlan was kidnapped & used as a power supplier for the Alliance. Together, the Alliance of Evil they acted as mutant terrorists for Apoclaypse. Initially they defied the Mutant Registration Act, which brought them into conflict with the original X-Factor team.
Eventually the Alliance of Evil disbanded, and Timeshadow's whereabouts since are unknown.
Timeshadow was created by Bob Layton and Jackson Guice in 1986 and first appeared in X-Factor # 5.
Timeshadow can teleport and displace himself in time a millisecond at a time, vanishing in the time stream and reappearing back in very rapid succession. The effect this causes is to present multiple images of himself without actually being any one of them (similar to a strobe light photograph). Timeshadow has a habit of phasing in and out of time-synch even when he is not in combat, making him extremely difficult to surprise.