The first thing I remember seeing Marion Cotillard in is
Love Me If You Dare (aka
Jeux d'enfants), a really good offbeat romantic comedy/drama. Looking at her IMDB page, I see that her first acting credit was a first season episode of
Highlander. I might have seen her in that, but don't recall doing so.
Anyway, she's a great actress and very pretty to boot, so thumbs up.