Void was put into C, but it was actually not necessary by itself -- the default return type was int, and if nobody was using the value there was no particular reason to use void. So only those who were practitioners of the strong-type religion tended to use it. A major problem in making C strongly typed was deciding on a return type for malloc. It had traditionally returned char *, but this required a cast to allow you to allocate things other than characters.

I was at a /usr/grp conference at the alcohol-fueled reception talking to Charlie Roberts about the problems of making C more strongly typed. The topic of malloc came up. All of a sudden Charlie got a huge grin on his face and said "Hey! Why don't we have malloc return void *". It took me a minute or two to even understand what void * could possibly mean, but the idea was an instant winner. I seem to recall it was done a week or two later. The idea may have simply ready to be born and others may have had it as well, but this is what I remember of it. And the experience sticks in my mind as being an almost literal example of being "struck by an idea".