So here's one from Jorge Garcia, who played Hurley on Lost:
"The original Hurley was like this 50 year old redneck guy. and then they saw me in "Curb Your Enthusiasm" where i played a pot dealer who sells pot to Lary David. and then they went "well, then again- maybe THAT."
And I went in and met the producers and I read sides for Sawyer- which ended up being Josh Holloway's part. And they ended up writing Hurley for me.
See, when I got hired, there wasn't even a script written yet. I just knew JJ Abrams and Hawaii. And really, that was enough for me.