Former NFL running back Hugh McElhenny -- whose #39 is retired by the San Francisco 49ers -- has passed away

the Pro Football Hall of Fame announced Thursday.

He was 93 years old. The Hall of Fame said McElhenny died of natural causes at his home in Nevada.

"We pass along our heartfelt condolences to his family, friends, and to the many whose lives he touched," The Hall wrote in a tweet when announcing the news.

McElhenny -- whose nickname was "The King" -- was taken by the 49ers with the 9th overall pick in the 1952 NFL Draft ... and he went on to star for the team for 9 seasons.

In his first NFL season (1952), McElhenny was unanimously elected Rookie of the Year 

and earned All-Pro status as well as a spot on the Pro Bowl team.

McElhenny's final year came in 1964 with the Detroit Lions, but he also played for the Vikings and Giants.

McElhenny -- who finished his career with 38 rushing touchdowns and 5,281 rushing yards _____R.I.P