The school newspaper at Douglas High in Parkland wrote to George Clooney asking if they could interview him. He said it would be best if the students took center focus and not the adults or the celebrities (though Clooney did attend with his wife and donated $500,000 to the event)
Paul McCartney attended the march but did not speak publicly though he did reference John Lennon as one of the reasons he showed up.
Stephen Spielberg and wife Kate attended (and donated)
One of the most dramatic moments was when Emma Gonzales took a 6 minute 20 second moment of silence...the amount of time the gunman spent in Parkland during his shooting ramage.
Miley Cyrus sang a most appropriate song