William Thomson Sloper (December 13, 1883 − May 1, 1955) was an American stockbroker and survivor of the sinking of the RMS Titanic. Sloper, who was 28 when the Titanic sank, traveled as a first-class passenger and was saved after boarding lifeboat #7, the first to be launched from the vessel. William Sloper was born in New Britain, Connecticut, son of Andrew Jackson Sloper and Ella Thomson Sloper. In April 1912, he was returning to the United States after a three-month vacation in Europe. The stockbroker and estate manager planned to travel on board the RMS Mauretania. However, while still in Europe, he met the Canadian family of Mark Fortune and became very fond of his daughter Alice, prompting him to cancel his tickets aboard the Mauretania and purchase tickets for the maiden voyage of the Titanic. On the night of the sinking, Sloper was playing bridge with other men when the Titanic struck an iceberg and began to sink. At first, he didn’t pay much attention to the turmoil on deck but as time passed he decided to leave the room and go up to deck. Since he thought that the Titanic was “unsinkable”, he first refused to leave, but ultimately gave in after insistence by actress Dorothy Gibson who urged him to go with her aboard lifeboat #7. He would credit her with saving his life after the disaster.

On April 19, 1912, one day after arriving in New York City aboard the RMS Carpathia, a tabloid newspaper identified him as one of the passengers who had dressed in women’s clothing to get their spot in the lifeboats. William Sloper would spend the rest of his life denying the accusations. After the disaster, Sloper became a managing partner of a private investment firm. He married Helen Tallmadge Lindenberg on February 26, 1915 in Columbus, Ohio and brought up her three daughters from a previous marriage. William Sloper died on 1 May 1955.