To call it that would be to give you the idea this is a comic, perhaps, or a shot of Miranda with her kit off. No, this is art that, while made by a fan, would be at home amongst professionals.
These pieces were done by Polish artist Patryk Olejniczak, and were born of his desire "to make one of the best [pieces of]fan art (which would also work as promo or poster art) to be had". You're getting pretty close, Patryk.
While he uses screenshots and character art for reference, Olejniczak says that he doesn't rely on things like tracing, 3D models or painting over screenshots to get these results. These are simply digital paintings. Beautiful digital paintings.
Mass Effect - Thane Krios [Garrett Art Lair]