From Halopedia, the Halo wiki
Dan Miller was a Bungie employee. While at Bungie, he worked as a campaign designer for Halo 3, Halo 3: ODST, Halo: Reach alongside various parts of the Destiny franchise. His first level at Bungie was the Halo 3 mission Crow's Nest, and later went on to work on the missions Halo (particularly the level's Warthog run), Tayari Plaza, NMPD HQ, Coastal Highway, New Alexandria and The Package. Miller also worked on the multiplayer maps Assembly and Sandbox for Halo 3's Mythic Map Pack and the Firefight mode and maps in Reach. Dan was also assigned to work on the cut Halo 3 levels, The Lost City and Guardian Forest.
Halopedia hosts a gallery of design documentation created and posted by Miller, which can be viewed here.