Alan Thicke passed away from a heart attack at the age of 69 on Tuesday. Since the news broke, stars have been taking to social media to express their sadness and memories of the beloved Growing Pains actor. Alan's Fuller House costar Bob Saget tweeted his condolences, writing, "So sad is the passing of Alan Thicke. Such a good husband, father, brother, and friend. He will be deeply missed. Rest in peace dear Alan." Lori Loughlin, Alyssa Milano, William Shatner, and his ex-wife Gloria Loring also shared touching messages. Alan is survived by wife Tanya and his three sons, Robin, Brennan, and Carter.