I worked as a tutor on the film set for the second Harry Potter. We were working with the children who made up the crowds at Hogwarts, not the main actors who had permanent school tutors, so were called in when there were crowd scenes to be filmed. As such it was understood that we were unlikely to see anyone famous. Except we did, on the day they filmed the duelling scene with Kenneth Branagh playing Gilderoy Lockhart and, of course, Snape. All of my group of children were on set so I could be as well.
First moment of being impressed: Draco couldn't get his moves right. A number of people tried to help, from the director to his brother (who was a stunt double). And then Rickman stepped forward, said a few words and you could almost see the (invisible) light bulb above Draco's head light up - he got it the next take. Second moment of being impressed: Rickman had been standing chatting normally with people. When asked to, he took up his position, adjusted his gown, flicked his hair back and suddently in front of us he completely transformed from Rickman to Snape. Took the breath away. Third moment of being impressed: later he had to move past a group of us. Charisma? Sex appeal? I've never seen so many grown women reduced to babbling idiots - seriously! And Fourth moment of being impressed: I had tickets later that night to see him on the West End stage in Private Lives with Lindsay Duncan, and there he was, hours after being Snape and working his socks off on the film set, being a wonderful light romantic character, singing and dancing and flirting.
I wish I had known him properly. Some heros are worth having. Loved his work, loved all I'm hearing about the human being. The world is a poorer place without him.