Board Thread:Warhammer 40k General Discussion/@comment-18016240-20140707161751/@comment-82.37.180.176-20150313002553

Kor Phaeron would surely be among the very oldest traitor marines.

In terms of loyalist marines who haven't been caught in the warp or incarcerated into a dreadnought, in Codex Angels of Death there is a special character called Sergeant Cleutin who was a Veteran Space Marine Sergeant when Commander Dante was a scout, and rumoured to be ancient. He is still an active marine as far as we know.