I think this has happened to most of us, one time or another. Often these drain bolts are over-tightened in an attempt to prevent drips and leaks, when a new crush washer is what is really needed.
As per the previous posts, there are quite a few ways to get it out. The last time I did one, I followed I believe Gilly's advice and got a sharp chisel, whacked a good indent on the edge in the counter-clockwise direction. It seems this is often enough to get it started.
The drain plug is designed to fail before the threaded portion of the oil pan. There are of course some exceptions to this, but generaly true.
Check with Sears.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)