PITTSBURGH -- Dick LeBeau, the architect of the defenses that were the driving force behind the Pittsburgh Steelers' three Super Bowl appearances from 2005 to '10, won't return to the team in 2015.

LeBeau, 77, told the Urbana Daily Citizen of Ohio that he has resigned as the team's defensive coordinator. A member of the Pro Football Hall of Fame, LeBeau has spent 56 seasons in the NFL as a player and a coach and the last 11 leading the Steelers' D.

"I'm resigning this position, not retiring," LeBeau told the newspaper. "I had a great run in Pittsburgh. I'm grateful for all the things that have happened to me and thankful for all the support I had in Pittsburgh."

The Steelers confirmed LeBeau's resignation later Saturday.

"We want to thank Dick for his many years of service with the team and all that he has done for this organization," Steelers coach Mike Tomlin said. "His coaching helped lead us to many successful seasons and championships. We are very appreciative of his efforts, and we wish him well."

A source close to LeBeau told ESPN.com that LeBeau is "OK" with leaving the Steelers and "ready for what happens next" but that he wanted to return in 2015.

The End of An Era Dick LeBeau was the longest-tenured defensive coordinator in the NFL when the season ended, having been with the Steelers since the start of the 2004 season. Three of the four longest-tenured defensive coordinators have either resigned or been fired this offseason. DC Team Started D. LeBeau* Steelers 2004 D. Capers Packers 2009 P. Fewell* Giants 2010 J. Haslett* Redskins 2010 *Fired or resigned since season ended --ESPN Stats & Information

Linebackers coach Keith Butler is expected to succeed LeBeau after garnering interest as a defensive coordinator around the NFL in recent years but deciding to stay in Pittsburgh.

Beloved by his players and hailed as an innovator with the zone blitz scheme he developed to counter run-and-shoot offenses in the 1990s, LeBeau spent two stints as the Steelers' defensive coordinator.

Pittsburgh allowed the fewest yards in the NFL in five of the 13 seasons in which LeBeau led the defense. His finest season with the Steelers came in 2008, when the defense finished first in the NFL in scoring, passing and total defense and second in rushing defense.

Outside linebacker James Harrison recorded 16 sacks that season and won The Associated Press Defensive Player of the Year honors. That defense led the Steelers to a 12-4 record in the regular season and their sixth Super Bowl title.

The Steelers' defense slipped over the last seasons as the team rebuilt it on the run after losing stalwarts such as linebacker James Farrior, nose tackle Casey Hampton and defensive end Aaron Smith, while injuries and age caught up to others such as defensive end Brett Keisel and strong safety Troy Polamalu.

The Steelers finished 18th in 2014 in both scoring defense (23.0 points allowed per game) and total defense (353.4 yards per game).

Veteran cornerback Ike Taylor was among a group of current and former Steelers players who reacted to the LeBeau news via social media Saturday.

Just a few good stats under DA GREAT LEBEAU...🙏👍👌🔥💯... pic.twitter.com/Q8bFanPXdh — Ike Taylor (@Ike_SwagginU) January 10, 2015

LeBeau's success in the NFL started long before he embarked on a career in coaching when he joined the Philadelphia Eagles in 1973 as a special teams coach.

LeBeau starred at cornerback for the Detroit Lions, intercepting 62 passes from 1959 to '72. He was inducted into the Pro Football Hall of Fame in 2010, and the Steelers' coaches and played traveled by bus from training camp in Latrobe, Pennsylvania, to Canton, Ohio, for the ceremony.

LeBeau coached for five different NFL organizations and served as the Cincinnati Bengals head coach from 2000 to '02. The London, Ohio, native coached the Steelers' defensive backs from 1992 to '94, and former coach Bill Cowher promoted LeBeau to defensive coordinator in 1995.

LeBeau left the Steelers for the Bengals' organization after the 1996 season and returned to Pittsburgh in 2004.

The Steelers played in four of their eight Super Bowls with LeBeau as their defensive coordinator.