Yes he was the last NHL player, playing without a helmet. See: http://www.oilersheritage.com/history/dynasty_players_craigmactavish.html
Craig MacTavish.
Brad Marsh
Craig MacTavish was the last "bare-headed" NHL player. He retired after the 1996-97 season and is currently the head coach of the Edmonton Oilers.
brad smith
Bob Shiek
I have no idea who the last five players were, but the very last one was Craig MacTavish, who is the current head coach of the Edmonton Oilers. His last season was with the St. Louis Blues in 1996/97. When he retired at the end of that season he was the last player to not wear a helmet.
Bob Montgomery , Boston Red Sox 1979
Felix Potvin (1993)
In 1988/1989 season, Ron Dugay was still not wearing a helmet. I believe he was the last King player to do so. The next year Dugay played for the San Diego Gulls so if it was not him it would have to be after that season.
You cannot tackle another player with your helmet. You can in fact tackle another player leading with your helmet...the rule is that you cannot make helmet to helmet contact with another player. That being said it is unsafe to lead with your helmet in any situation due to injury probability, you risk neck and head injuries when you lead with your helmet.
Willi Plett, Brad Smith, Guy Lafleur