In a strong argument for the existence of alternate realities, according to this purported 1987 Star Trek: The Next Generation casting sheet Wesley Snipes was once a front-runner to play Geordi La Forge.
This is nothing against LeVar Burton. I love LeVar Burton! And I wouldn't have wanted to see anyone else in that role over the long-run. But just imagine how different life aboard the Enterprise would have been with Simon Phoenix as chief engineer.
Now, the veracity of this list is certainly in question; the originating site, Slice of SciFi, isn't very forthcoming with its provenance. And a few of the people who ended up on the show (Brent Spiner? Wil Wheaton?) aren't listed here as candidates. So grain of salt, etc.
To be honest, part of me secretly hopes it's a fake; I get a little queasy just thinking about how close we were to Patrick Bauchau telling Michael O'Gorman to "make it so." Whoever they are. [Slice of SciFi via Letters of Note]