Fans of the History Channel series will recognize esoteric investigator Phillip Coppens.  He passed away from cancer on December 30, 2012.

Coppens was interested in alternate history and wrote books like 'The Canopus Revelation' and 'Servants of the Grail'.

The 'Ancient Aliens' series made the following statement on Facebook:

All of us who are involved in the production of Ancient Aliens are deeply saddened by the passing of our friend and frequent contributor, Philip Coppens. Philip's contribution to the series has been enormous and his insights have helped further the argument that mankind's journey to discover his true origins has only just begun. He will be missed, but he will always be treasured.

Phillip Coppens on Atlantis:

Phillip Coppens discussing Ancient Aliens: