A miller is a person who operates a mill, a machine to grind a grain (for example corn or wheat) to make flour.

"Miller", "Milne" and other variants are common surnames,[1] as are their equivalents in other languages around the world ("Melnyk" in Russian, Belarusian & Ukrainian, "Meunier" in French, "Müller" or "Mueller" in German, "Mulder" and "Molenaar" in Dutch, "Molnár" in Hungarian, "Molinero" in Spanish, "Molinaro" or "Molinari" in Italian, "Mlinar" in South Slavic languages etc.).

As technology and millstones (the bedstone and rynd) improved, more elaborate machines such as watermills and windmills were developed to do the grinding work.

As an important part of his job, the miller repeatedly takes into his hand samples of the ground meal coming out of the spout in order to feel the quality and character of the product.

The European bullhead (Cottus gobio), a freshwater fish, is commonly called a miller's thumb for this reason.