Ronald Martin Hainsey (born March 24, 1981) is an American former professional ice hockey defenseman.

He played seventeen years in the National Hockey League (NHL) for the Montreal Canadiens, Columbus Blue Jackets, Atlanta Thrashers, Winnipeg Jets, Carolina Hurricanes, Pittsburgh Penguins, Toronto Maple Leafs and the Ottawa Senators, playing over 1,100 career NHL games.

Hainsey played in the NHL for nearly 16 years (907 games) before a late season trade to the 2016–17 Pittsburgh Penguins saw him play on a team that made the playoffs, longer than any other player in league history, beating the previous record of 799 games held by Olli Jokinen.

[7] After spending three seasons with the Canadiens organization, Hainsey was claimed off waivers on November 29, 2005, by the Columbus Blue Jackets,[5] where he established himself as a solid two-way defenseman.

[11] He was a key part of the negotiating team for the National Hockey League Players' Association (NHLPA) in the lockout.

[14] On September 12, 2013, Hainsey signed a one-year, $2 million contract with the Carolina Hurricanes after the team announced that a defenseman Joni Pitkänen would miss the season due to injury.

[16] On February 23, 2017, Hainsey, in the final year of his contract, was traded to the Pittsburgh Penguins in exchange for a second-round pick in the 2017 NHL Entry Draft and Danny Kristo.

[18] An unrestricted free agent following the season, Hainsey signed a two-year, $6 million contract with the Toronto Maple Leafs on July 1, 2017.