I used to work in a building named after Arthur C Clarke, and was lucky enough to meet him there once. The building had been opened by him "remotely" from Sri Lanka, and he had promised to come round if he was ever in the UK and had time to visit. One day he had a bit of spare time, and arrived unannounced. First I knew about it was when he arrived at my desk (it was the first one outside the lift, so he picked me to talk to!). Fascinating person, and it's a great shame that he's not more widely recognised for his work.