"We mourn the loss of Erin," Spurs general manager RC Buford said in a statement provided to Bleacher Report. "She was a strong, wonderful, kind, intelligent woman who provided love, support and humor to all of us."
Erin and Gregg Popovich were married for four decades. She is survived by the Spurs coach, their two children and two grandchildren.
ESPN.com's Adrian Wojnarowski noted she had been dealing with an undisclosed illness for an "extended period."
While he rarely talked about his personal life, Popovich shared an anecdote in 2012 about Erin chastising him for his contentious relationship with sideline reporters.
"It entertains everybody but my wife," Popovich said on Dan Le Batard's radio show (via USA Today). "When I get home and she says, 'Geez, why are you so mean? You're a jerk, people hate you.' I go, 'I'm sorry, honey, I have to do better next time.'"
"And there's no exaggeration. 'Did you see that guy, honey? Did you see him? All you have to do is see him and you know why I answered the way I did.' [She says], 'That's no excuse, you're a grown man. Show some maturity.' I said, 'I can't, I can't do it.'"
Popovich's status for the Spurs' Game 3 matchup with the Golden State Warriors is unknown at this time. San Antonio is down 2-0 in the best-of-seven first-round series.