"We miss you already, Kobe," New England Patriots quarterback Tom Brady tweeted.
"I'm so sad and stunned right now," John Legend tweeted.
Bryant, 41, an 18-time all-star and a five-time NBA champion with the Los Angeles Lakers, died Sunday morning when the helicopter he was traveling in crashed and burst into flames in foggy conditions in the hills near Calabasas, the Los Angeles Times reported.
The San Antonio Spurs and Toronto Raptors both held the ball for 24 seconds during Sunday’s game, a nod toward Bryant’s No. 24. The Raptors took a violation after winning the tip, and the Spurs followed suit.
Along with the tributes came disbelief.
"I'm stunned," former Chicago Bulls star and NBA Hall of Famer Scottie Pippen tweeted. "Words can't even come close to describing it. Just an incredibly sad and tragic day."
"This is not real right now," Paul Pierce tweeted.
"Somebody tell me it ain't so!" former NFL and major league baseball star Deion Sanders tweeted.
Shaquille O’Neal, Bryant’s teammate with the Lakers from 1996 through 2004, tweeted in capital letters, “I’m sick right now.”
The NBA Players Association, in a statement, called Bryant’s death “a monumental loss for the entire basketball community."
"Our hearts are quite simply broken," the organization tweeted.
President Donald Trump tweeted called reports of the crash was "terrible news."
Bryant scored 33,643 points in his 20-year NBA career. He retired from the Lakers after the 2015-16 season after spending his entire career with the franchise.
Kareem Abdul-Jabbar, the NBA’s all-time leading scorer, told CNN that Bryant was “an incredible family man.”
“He was an incredible athlete and a leader,” Abdul-Jabbar said.
Pat Riley, Bryant's coach in Los Angeles, is now president on the Miami Heat. The team tweeted its condolences on Twitter.
The crash comes one day after Bryant was passed by Lakers forward LeBron James for third place on the NBA’s all-time scoring list.
Hollywood also reacted with dismay at the news, with Octavia Spencer, Chrissy Teigen and Nick Jonas among the celebrities sharing their grief.
“RIP Kobe! My thoughts and prayers are wirh (sic) your family,” Spencer tweeted.
“This is heartbreaking," Jonas tweeted. "Rest in peace Kobe.”