-Bought the creators of Portal
You know, the whole Valve doesn't make games thing has been trodden billions of times already, but this one always bugs me the most. Valve didn't hire the people who made Portal. They hired some people who made a small student game called Narbacular Drop. Narbacular Drop freakin' looks like this.

Those few new hires didn't enter Valve and then singlehandedly make Portal (it's assets, it's characters, etc) without any input from the other prior dozens of Valve employees. The company saw a cool gameplay idea, hired the developers instead of just taking the idea and using it, and then formed a team of people to make the game. Portal is a Valve grown product!