Patrick Henry McCarthy (March 17, 1863 – July 1, 1933), nicknamed "Pinhead", was an influential labor leader in San Francisco and the 29th Mayor of the City from 1910 to 1912.

It fought off the efforts of employers in San Francisco to impose the open shop on construction workers in the first decade of the twentieth century and was active in local politics.

The BTC was able to turn this control at the workplace level into better wages in the San Francisco construction industry than anywhere else in the country in the first decades of the twentieth century.

The BTC was able to do this, moreover, without fighting the drawn-out battles that unions elsewhere had to wage simply to obtain recognition or preserve their rights: only two building trades strikes in San Francisco between 1901 and 1921 lasted more than a week.

McCarthy ruled the BTC like an autocrat: he did not brook criticism, much less challenges to his authority, and he sometimes made decisions concerning local unions without consulting the parties involved.

His high-handed style served him for many years, but created enough resentment within the BTC that eventually forced him to resign from its presidency in 1922, following the loss of a strike that allowed the open shop to return to San Francisco in 1921.

While the criminal proceedings were still underway, and during the midst of a bitter strike by San Francisco streetcar workers, McCarthy ran on a platform of promising to halt the ongoing prosecutions.