My 3e gnome conjurer only learned spells from the conjuration school. His name was "Whisper" and he only whispered. His raven familiar did most of the talking. I actually had a life-sized raven puppet, that I used during the games for the raven.
The raven "Crass" fancied himself a thief, and successfully picked a lock (that the party badly needed picking) and successfully killed an enemy (1 HP left, but he was going to kill another PC). He actually got XP for it, though he didn't get enough to "earn" a 1st level as Rogue.
My 2e f/t/m half-elf once bought a bar from the owner for 30,000 GP, when he found it surrounded by enemies. Just so he could kick everyone out, invite the enemies in and fireball it as he jumped out the second floor. He was destructively considerate that way.
My 3e half-orc Barbarian of deadly rage silently fumed for 3 hours of real time/game time as the rest of the party chatted with a gnome labtech as he gave them a tour of this amazing research facility, when in reality he was the evil gnome illusionist mastermind who was grabbing his notes before he bailed on us. When he vanished, I shouted, "I knew I shouldn't have chopped his head off the moment he started talking!" So, basically, I role-played for 3 hours a person quietly spending 3 hours repeatedly thinking "I should kill him now. I should kill him now."
I think I had been further irked by the fact that the party had spent the previous 3 hours going over the budget and planning for the city they just took ownership of (wherein they discovered the hidden facility). Basically, 6 hours had gone by without killing anything.
Personally, I think role-playing silent raging for 3 hours is my best "in character" example. The other players knew it, because they were deliberately pointing out "you know, we haven't killed anything yet this game..."
