Jorge Silva/Reuters
Olympic gold medalist Michael Phelps was bullied as a child.
Successful people are rallying around Keaton Jones, a Tennessee middle-school student who described the bullying he's endured in a video that has gone viral.
In many cases, the celebrities hailing Jones for coming forward were once the victims of childhood bullying themselves.
For instance, Mark Ruffalo tweeted at Jones: "Little buddy, I was bullied when I was a kid. You are right #ItGetsBetter! You are my own personal super hero. Protect Yo Heart. You got a pal in the Hulk."
From Elon Musk to Justin Timberlake to Rihanna, bullying has shaped the experiences of countless successful people.
Here are nine of the celebrities who know what Jones is going through: