The Eagles mourn the loss of Hall of Fame tight end Pete Retzlaff, a co-captain of the 1960 NFL Championship team and one of only nine players in franchise history to have his jersey number retired. Retzlaff, who remained a fixture in the Philadelphia community long after his Eagles career, passed away in Pottstown, Pennsylvania on Friday morning due to natural causes. He was 88 years old.

"We are saddened to learn of the passing of Eagles Hall of Famer Pete Retzlaff. Pete was a revolutionary tight end and one of the most productive players in the history of our franchise," Chairman and CEO Jeffrey Lurie said. "He was a five-time Pro Bowler, a key contributor on our 1960 Championship team, and of course his number 44 was retired after he established numerous receiving records over his 11-year career. But Pete's legacy goes far beyond the success he was able to achieve on the field. He gave so much to this organization and to our sport as a player, general manager, broadcaster, and leader of the NFLPA.

"He stayed connected with the team and the city of Philadelphia for many years after his retirement. I had the pleasure of spending time with Pete over the years and I will always remember him as a true gentleman who was kind and genuine and who connected so well with others. On behalf of the organization, our thoughts are with Pete's family and friends as we mourn the passing of an Eagles legend."

Retzlaff is survived by his wife of 66 years, Patty, four children – daughters Kris Schroeder (husband George), Daniene Skean (husband Samuel), and Carol Moser (husband Dale), and one son, Jim – 10 grandchildren (Rebecca Carr, Laurie Price, Emily Jones, Matt Schroeder, Billy Moser, Kacy Brobst, Erin Moser, Benjamin Skean, Maddy Moser, and Colin Retzlaff), and 12 great-grandchildren.

"Pete was proud to have played his entire career in Philadelphia," the Retzlaff family said in a statement. "Our family can't thank the Eagles and the wonderful fans enough for their support that bolstered his playing years and beyond.

"Pete set lofty goals for himself. He believed in hard work, honesty, and always giving 100 percent effort. Throughout his life, he believed in giving back to the community as a thank you for what they gave to him. Thank you to all of Philadelphia."

A 22nd-round pick of the Detroit Lions in 1953 out of South Dakota State, Retzlaff served two years in the Army before the Eagles claimed him off waivers in 1956. The Eagles converted Retzlaff from fullback to tight end and he earned five Pro Bowl selections in 11 seasons with the team. He retired following the 1966 season as the franchise's all-time leader in receptions (452) and receiving yards (7,412). Today, Retzlaff ranks tied with Brent Celek for first in most seasons played by a tight end, second in receiving yards to Pro Football Hall of Fame wide receiver Harold Carmichael, third in receptions behind Carmichael and Zach Ertz, and fifth in receiving touchdowns.

Nicknamed "The Baron" by teammate and fellow Eagles Hall of Famer Tom Brookshier and "Pistol Pete" by the former Voice of the Eagles Bill Campbell, Retzlaff was inducted into the team's Hall of Fame in 1989. His No. 44 jersey is one of only nine retired by the Eagles.

"Pete was one of the first tight ends with enough versatility to be a receiver as well as a blocker. He changed the game because defenses had to alter their coverages to guard him," said Eagles Hall of Fame linebacker Maxie Baughan.

In 1958, Retzlaff tied with Pro Football Hall of Famer Raymond Berry for the NFL lead with 56 receptions. Two years later, Retzlaff led the Eagles with 46 receptions and averaged 18 yards per catch as the Eagles captured their third NFL title. In the epic NFL Championship win over Vince Lombardi's Packers, Retzlaff's 41-yard reception resulted in a field goal that gave the Eagles a 10-6 lead late in the first half.

Retzlaff redefined the position with his 6-1, 211-pound frame as he not only could block, but he could also stretch the field as a receiver. Once he had the ball in his hands, his fullback background shined through in his ability to get yards after the catch. For his stellar career, he averaged 16.4 yards per catch and lost only four fumbles.

"He was a great route runner, more like a wide receiver than a tight end. Many times, I had to grab his shirt as he ran by me. He was a quiet guy, never brought attention to himself, but a very tough competitor," said Cowboys Pro Football Hall of Fame safety Mel Renfro.

Retzlaff earned first-team All-Pro honors in 1965 when he gained 1,190 receiving yards, the most by a tight end in franchise history. He was named the NFL's Player of the Year by the Maxwell Club as well as the recipient of the Wanamaker Award for the best athlete in Philadelphia. Retzlaff is the only tight end to ever win the Maxwell Club's NFL's Player of the Year Award.

Berry said at the time that it was "the best season a tight end ever had."

The Ellendale, North Dakota native was also instrumental in the founding of the NFL Players Association. Three years after his playing career ended, he returned to the Eagles in the role of general manager from 1969-72.

Previous reporting from Ray Didinger and Jim Gehman was used in this story.