These are only estimates since my cd collection is scattered everywhere:
John Zorn – I bought everything that he released for a while, including all the Naked City, Masada, game theory pieces, Filmworks, etc., until 2003 or so. I now buy one or two every now and again, but I checked recently and there had been 27 releases since I stopped buying everything that I didn’t have. I probably have 40 Zorn-related cds.
Bjork – While she only has, umm, 6 or 7 studio albums, there is also the three with the Sugarcubes (plus the best-of), the two with Kukl, all of her concert and music video DVDs, and all the greatest hits and other repackaging things I have bought by her.
Ennio Morricone – I bought maybe 15 or so actual soundtrack albums with him as the composer, but I have bought at least double that many Morricone compilations that span his entire career.
Eric Dolphy – I think I have everything that has been commercially released with him as a player, but I have no clue how to be sure of that. There’s only a limited number of albums where he was the leader, but then there’s the stuff with Coltrane, Ornette, etc. I bought a 9-disc compilation that I thought had filled in all the holes from the dozen or so others I had bought singly, and he’s actually been dead since I’ve been buying so I’m not helping him out any.
Kronos Quartet – They have a lot of releases, and I haven’t kept up lately (there’s something new called Floodplains which I hadn’t heard of until just now), but I have at least 20 releases by them.
Swizz Beatz – He’s a rap producer who only has two albums to his name, but I bought pretty much every release by every rapper where Swizz had produced more than two songs on it. Which is a lot – I can’t figure out how many, but it definitely rivals at least the number of Bjork albums I have.
I think those are the heaviest hitters in my collection.