Thomas Joseph Mooney (December 8, 1882 – March 6, 1942) was an American political activist and labor leader, who was convicted with Warren K. Billings of the San Francisco Preparedness Day Bombing of 1916.

His father, Bernard, had been a coal miner and a militant organizer for the Knights of Labor in struggles so intense that after one fight he was left for dead.

Bernard Mooney died of "miner's con" (now known as silicosis) at the age of 36, when Tom, the eldest of three surviving children, was ten years old.

After arriving in California, he met his wife Rena, and found a place in the Socialist Party of America and the presidential campaign of Eugene V. Debs.

[1] In 1910, Mooney won a trip to the Second International Conference in Copenhagen by selling a huge number of subscriptions to the socialist Wilshire Magazine.

[citation needed] Ten deaths and forty injuries resulted from the explosion in the midst of the Preparedness Day parade.

During that time his wife Rena, Bulletin editor Fremont Older, anarchists Alexander Berkman and Emma Goldman, Lucy Robins Lang, heiress Aline Barnsdall, Hollywood celebrities, international politicians, and many other well-known people campaigned for his release.

[7] In 1931, New York City Mayor Jimmy Walker made a solidarity visit to Tom's sister Anna's house in San Francisco's Mission District.

He had not worn his martyrdom well; he broke with modest Billings, who was convicted with him but somehow was never regarded as a martyr; he was estranged from his wife; his former colleagues in the labor movement often found him to be selfish and conceited.