The 95-year-old former president of South Africa died Thursday at his Johannesburg home, according to CNN.
Upon hearing the news, President Barack Obama issued a statement, calling the beloved leader one of the "most influential, courageous and profoundly good" people to ever have lived.
"He achieved more than could be expected of any man," Obama said. "He belongs to the ages."
Nelson, who spent 27 years in prison in South Africa opposing apartheid, later went on to become the first black president in South Africa and win a Nobel Peace Prize.
Take a look at more stars' tributes to Nelson Mandela.
Rihanna: "One of the greatest men who's ever lived!!! #Legend We will never forget the things this man has taught us, and we will never truly comprehend the level of strength that it took for him to endure many of his years!! Thank you #Mandela"
Beyoncé: "Thank you for all you have sacrificed to improve the lives of other human beings. Rest in peace."
Samuel L. Jackson: "Never met a better person in my life than Nelson Mandela. My sympathy to his family & his country."
John Legend: "What a heroic, beautiful life Mandela lived. Rest in peace."
Lindsay Lohan: "A good head and a good heart are always a formidable combination." #RIPNelsonMandela
Tyra Banks: "He lives within us forever. We will never forget."
Ludacris: "Honored that I had a chance to meet this amazing influential being & to participate in his 46664 Aids benefit concert in South Africa. You will live on thru your work for eternity. R.I.P. Nelson Mandela"
Pitbull: "RIP Nelson Mandela. You are now truly free. God Bless and enjoy the heavens. Tell Celia Cruz hello for me and azucaaaaarrrr"
Josh Groban: "We have lost one of humanity's greatest treasures. RIP Madiba. I will never forget the lessons learned from him or his vision that lives on."
Kendrick Lamar: "Advising all my young ones that follow me to research a small piece of Nelson Mandela Life. That's how you pay your respect...... GO!"
Kelly Osbourne: "Today is officially one of the saddest days! The world has lost the most inspirational person to ever walk the earth rip #NelsonMandela"
Eva Longoria: "Today the world lost one it's greatest leaders. Rest in peace Mandela..."
Olivia Wilde: "Oh Mandela, rest in peaceful freedom."
Ryan Phillippe: "What an amazing life lead by Madiba. A light & inspiration to the world...The privilege of spending a small amount of private time w/ Mr. Mandela as he held my baby daughter, is a highlight of my life...It was like being in the presence of a diety. He truly emanated warmth and humanity. Imperfect, like us all, but w/ a strength few possess...Mandela was bouncing Ava, then two yrs old, on his knee & called her, "future leader". I couldn't believe it in that moment. I still can't."
Abigail Breslin: "Speechless... R.I.P. Nelson Mandela."