
MacFraggin |

Oh, quite a few come to mind.
- I've seen a 3.5 Ranger that insisted on fighting with Dual Scimitars, while refusing to pick Humans as Favored Enemies. My Cleric wasn't even particularly optimized and still outdamaged him (in addition to everything else that Clerics do).
- or how about the OA Samurai that, at level 10, sported an AC of a whopping 18? Enemies literally couldn't miss him on anything but a 1.
- in Pathfinder, an Oracle that didn't wear armour - I guess the player went only by the illustration and simply didn't bother to read up in the proficiencies.
But who I think takes the cake:
The Gunslinger who fought with Cutlass and Pistol and did 1d6+0 with either attack. Well, so far I can't really blame him, it's just bad design on behalf of Paizo when a class can't do its own shtick before level 5.
However, this being a seagoing campaign, the player refusing to invest a single skill point into either Swim or Prof:Sailor, that I do blame him for. He was so utterly useless both in and out of combat, it was just painful.