#1 David W. Mack, the comic artist and writer.
#2 David Alan Mack, primarily known for his tie-in novels.
(These two both normally go by just "David Mack", but have a gentleman's agreement to use the differentiating middle name when approaching each other's "territory"-- for example, David Alan Mack used his middle name in the byline for his Wolverine novel, Road of Bones.)
#4 David B. Mack, Timber Milling in Australia: The Shepherdsons, 1849-1984.
#5 David Mack, Buzzfeed reporter.