Howard's Happy Days co-star, Henry Winkler, 66, also tweeted, "RIP the forever in our memory Andy Griffith."
Griffith died at his home in Manteo, N.C. Tuesday morning. He is survived by his third wife, Cindi Griffith, whom he wed in 1983.
"Andy was a person of incredibly strong Christian faith and was prepared for the day he would be called Home to his Lord," Cindi said in a statement via CNN. "He is the love of my life, my constant companion, my partner, and my best friend. I cannot imagine life without Andy, but I take comfort and strength in God's Grace and in the knowledge that Andy is at peace and with God."
Read more condolences and memories from Hollywood stars below.