There are plenty of artists out there whose work can be considered puzzling, but it's rare for any of them to actually make their art from puzzles. Doug Powell's mosaic artworks, which he calls Duzzles, feature pop culture icons like George Burns, Lady Gaga and more traditional works like the Statue of Liberty and flowers.
His portraits are made entirely of puzzle pieces, which he does not modify from their original design, other than occasionally trimming them a bit in order to accentuate details in a piece. To accomplish this, Powell needs quite a collection of puzzle pieces. The artist claims he has a standing collection of around a million pieces, enough to fill a small swimming pool.
See more examples of his work here.