The "Iron Claw" actor credited Perry, who died in October, with helping to "propel me and motivate me in so many ways.”
They expressed admiration for her lifelong service and mental health advocacy.
“Hug your loved ones,” wrote Pratt. “Reach out to that person that’s been on your mind. Life is fragile, precious and finite. Embrace it and one another.”
Sam Neill, John Travolta and Vanessa Hudgens were among the many Hollywood icons who publicly mourned the “Everwood” star.
The Safdie brothers and Kim Coates were joined by countless others who shared memories of the late star online.
The LGBTQ nightclub in Colorado Springs will honor the five who were killed in the mass shooting in November when it reopens.
"He gave me the gift of family," the Grammy-winning singer said. "I will forever be grateful."
“He ended up being sort of a bond for the whole family.” Former President Barack Obama reflected on how much their beloved dog Bo meant to them.
The actor wrote a tribute to his "Grease" co-star, Olivia Newton-John, 73, after her death was reported on Monday.
Some 1,400 mourners gathered Wednesday to celebrate her life and accomplishments at Washington National Cathedral.