Ron Wilson spent seven years as the fourth line centre for the Winnipeg Jets (1981-82 to 1987-88). The last six of those years Dale Hawerchuk, Thomas Steen and Laurie Boschman were the top three centres always in the same order. That's incredible continuity down the middle. Wilson then spent five more years as a fourth liner in St. Louis and Montreal.
If not fighters or guys valued primarily for fighting... Craig Adams, Dan Bylsma, Jeremy Stevenson, Grant Marshall, Turner Stevenson, Kevyn Adams, Rene corbet, Stephane Veilleux, Jamal Meyers, Scott Nichol, Kris King.
Marshall was usually a 4th liner, I think, but he played on a scoring line for a Cup winner (as a physical presence), so I don't think he counts as a career 4th liner.