Is there really anyone here who didn't know this already? The Morris worm is as much an essential part of Internet history as the development of BSD UNIX, the creation of the Web, or the millenial dot-com bubble.
I knew about the worm but I'm not exactly a fan of the person so I had no idea he was a co-founder of Y Combinator. Next think I know you'll be telling me that a movie actress helped invent a torpedo guidance system.
It's a bit sad that most people know of Morris for his destructive, rather than constructive actions, but Paul Graham seems to be more of the 'face' of YCombinator.
However destructive the Morris worm may have been, my understanding is that it wasn't deliberately so. I'd say it falls very much into the traditional hacker style of "creative endeavours".