I’m not one for labeling music in genres, so I’ll write my answer in two parts: the “canonical” information, with artists documented as “IDM” artists on Wikipedia, and the “personal” information, which I think fits the so called “IDM” genre, but don’t quote me on that, I wouldn’t really know. This is “best effort”.

Canonical answer:

Orbital, aphex twin, and boards of Canada come to mind, but that’s more for the curious casual reader of this thread, as I’m sure you already know them. Also John Tejada, Carbon Based Lifeforms, Moderat, which are less known.

Personal answer:

I dunno if I would say that they fit in “IDM”, but I really enjoy the music of the artist Siriusmo. Also (in no particular order, all this could be hit or miss for you, so don’t dismiss it all because you don’t like one) Sasha, Kaito, Ernest Saint Laurent, Vessels, Barker & Baumecker, and pretty much everything under the labels monkeytown and Kompakt (respectively based in Berlin and Koln). I’m not sure where the genre lines stop tho, so you might add nick warren, Phil k, Dave seaman, John Digweed, etc. to that. Labels renaissance (the British one) and Global Underground.