AbdulAlhazred
Legend
Right. And MC'ing Rogue or Assassin or Monk a couple of times can get you Thievery and Stealth while generally being useful. Monk's ability to power swap for Quicksilver Motion in particular is awesome.
Right. You could probably also do a rather nice Swordmage-based 'thief', though the defender role might feel a bit of an odd one to be cast in as a roguish sort. I'm not so up on Avenger and whether a high dex version would cut it too well or not, but that might be another fairly magical-seeming blade-armed guy with no/light armor that could feel pretty thiefy. Then of course there's always bladesinger too, as much as it gets panned by some.
I bet you could spin a barbarian into something kinda interesting too, lol. Granted the 'magic' would be more of the "I take your head off with a single swipe" sort...
How about a druid? hehehehe, wildshape would be kinda handy for a thief, though there are of course many other ways to get shape-changing. Druids have some pretty easy access to limited flight too, which would be nice for a burglary type.