Kenneth Nichols O'Keefe (born July 21, 1969) is an American-Irish-Palestinian citizen and activist and former United States Marine and Gulf War veteran. In 2001 he set fire to his United States passport. Subsequently, he led the human shield action to Iraq and was a passenger on the MV Mavi Marmara during the Gaza flotilla raid. He participated during clashes on the ship including the attacking of two Israeli commandos.
O'Keefe served as a United States Marine in the Gulf War. According to his own website, he was discharged because he "spoke out openly about abuse of power by my 'superiors' and as a consequence I paid a heavy price. I realised that honour and integrity were virtues which are often punished rather than rewarded and the Marines supplied me with my first serious taste of injustice."
O'Keefe created a marine conservation social enterprise "to protect and defend the marine environment" in Hawaii in 1996. This enterprise conducted ghost net recoveries and rescues of endangered Green Sea Turtle wrapped in monofilament fishing line. O'Keefe became a pioneer in sea turtle rescues in Hawaii and led a campaign to create a marine sanctuary (Pupukea MLCD) on the North Shore of Oahu.
In 1998 he joined an anti-whaling campaign in which he was bloodied when attempting to retrieve a boat belonging to the Sea Shepherd Conservation Society, of which he was a crew member. At this time he was being mentored by Paul Watson. Eventually he served as the regional director for the Sea Shepherd Conservation Society, in Hawaii.