Currently we're playing Dungeons and Dragons at a level 19 campaign (I'm level 20 as my character isn't leading any sort of army)
Our group is:
1 barbarian (my character)
When it came time to pick a tank for the group, you'll never guess who they chose. I have the highest hit points of the party but am not built as a tank. The barbarian class is a striker not a defender like a fighter is anyway; they don't have the same sort of mechanics like marking and stuff.
Our group also doesn't have a healer, somehow we haven't died horribly. The gm tends to give that 1000yard stare that people get whenever they know their carefully crafted plans are completely out the window. For instance, we did a one off game at level 1 two weeks ago when our normal gm wasn't there, the substitute said they had come up with a good game. What ended up happening was the paladin died in a bar fight after trying to steal somebody's enchanted beer stein. Another time somebody went completely away from the plot, killed some plot-important npcs, drained them of blood, made a shrine to an obscure deity and spent the rest of the campaign claiming to be doing the bidding of their made up god.