Denis A. Hayes (1860 – January 2, 1917) was an American labor union leader.

Born in County Clare in Ireland, Hayes emigrated to the United States with his family, when he was seven years old.

In 1894, he was elected as vice-president of the union, and in 1896 as president of what became the "Glass Bottle Blowers Association of the United States and Canada".

[2] In this role, he was prominent in the campaign against child labor.

[2] For the last 22 years of his life, he lived in the Hotel Windsor.