Robert Zoellner is an American stamp collector and the second person to have formed a complete collection of United States postage stamps. Benjamin K. Miller had assembled a complete collection pre-1925. As of November 2005, one other person, William H. Gross, has also formed a complete collection of US postage stamps.
Zoellner collected stamps as a child, but only began building his collection in earnest in 1985. He completed the collection in 1996 and it was auctioned off in 1998.
Read more about Robert Zoellner: Stamp Collection, Sale, References and Sources