I originally posted this in the IWD series forum but I think posting here might be a better idea.

https://imgur.com/ASM1RQ3

I got these from ebay and the seller was unsure where they came from originally also.

I know IWD 2 had a special release called Adventurer's Pack which contained similar cards, but I'm not aware of any special edition of IWD 1 that would feature these.

I'd love to hear from anyone who might know about their origin, were they given away in some stores as a bonus? Something else?

Looks like a set of promo cards.
All I could find online are these: (see attachment).

They're looking the same as yours (basic appearance, not the motifs), also as yours they apparently came in a set of eight cards (though the picture only shows seven), and featured the following characters:

Orrick the Grey
Accalia
Hrothgar
Aldwin
Oswald Fiddlebender
Amelia
Priestess of Auril
Hildreth Highhammer

Edit: apparently these eight cards were included in a magazine called "Dragon Magazine" to promote the release of the Icewind Dale CRPG.

The Dragon magazine lead is the best I've found so far, thanks a lot for it. I did some digging through the archives for both Dragon and Dungeon magazines around the year 2000 but found no mention of the cards anywhere, though I did find some ads for IWD. They could have been included without mention, stuck to the full page/cover ad.

I wonder if Dragon got the character cards and Dungeon got the cards that I have? It's just my guess, still looking for a definitive answer.