William Dudley "Big Bill" Haywood (February 4, 1869 – May 18, 1928) is a founding member and leader of the Industrial Workers of the World (IWW) and a member of the executive committee of the Socialist Party of America.

During the first two decades of the 2twentieth century, Haywood is involved in several important labor battles, including the Colorado Labor Wars, the Lawrence Textile Strike, and other textile strikes in Massachusetts and New Jersey.

Haywood is an advocate of industrial unionism, a labor philosophy that favors organizing all workers in an industry under one union, regardless of the specific trade or skill level; this is in contrast to the craft unions that are prevalent at this time, such as the AFL.

He believes that workers of all ethnicities should be united, and favors direct action over political action.

Haywood is often targeted by prosecutors due to his support for violence.

An attempt to prosecute him in 1907 for his alleged involvement in the murder of Frank Steunenberg fails, but in 1918 he is one of one hundred and one IWW members jailed for anti-war activity during the First Red Scare.

He is sentenced to twenty years.

In 1921, while out of prison during an appeal of his conviction, Haywood flees to the Soviet Union, where he spends the remaining years of his life.