Here's what I've got in my collection, taken from all over the internet. Hopefully one of them fits the bill, even if they're not explicitly a thief or a fighter (or half-elf, lol). The style varies a bit, but they're all vaguely BG-ish, at least. None of the images are mine, so hopefully no one minds me sharing them. I should have tried to keep track so I can give credit!
Other artists' portraits can be shared here as long as the artist is credited. If you don't know who made the portrait, a google reverse image search should get you there in a few seconds.
@energisedcamel Hmm. The only one that I feel would fit is the Grey Warden one, but I specifically didn't choose that one because it looks like a very obvious mage. Still, thanks for sharing the portraits.
@ThacoBell You're right. I've edited my post so it includes a link to the original artist of the portrait I posted.
Comments
http://isandir.com/altan/
https://forums.beamdog.com/discussion/51971/sycamirages-ultimate-guide-to-baldurize-your-portrait
https://www.deviantart.com/enkida/art/BG2-NPC-Kova-282926366
http://isandir.com/elvandrin/
http://isandir.com/elvandrin/
https://forums.beamdog.com/discussion/5339/alternate-npc-and-pc-portraits-because-i-m-bored-while-waiting-for-more-patches-to-come-out-p/p51
https://forums.beamdog.com/discussion/5339/alternate-npc-and-pc-portraits-because-i-m-bored-while-waiting-for-more-patches-to-come-out-p/p51
https://forums.beamdog.com/discussion/5339/alternate-npc-and-pc-portraits-because-i-m-bored-while-waiting-for-more-patches-to-come-out-p/p51
http://isandir.com/vihane-sodalane/
http://isandir.com/vaas/
https://www.deviantart.com/enkida/art/BG2-NPC-Tsujatha-282420717
Edited with the links - good idea @ThacoBell
@ThacoBell You're right. I've edited my post so it includes a link to the original artist of the portrait I posted.