Joseph Sebastian Cabot (October 8, 1796 – June 29, 1874) was a Massachusetts banker and politician who served as the fourth Mayor of Salem, Massachusetts.

[1] In 1838, Cabot's name was submitted for a fourth consecutive Democratic nomination to the United States House of Representatives from the south Essex County district, but the district convention at Salem chose Robert Rantoul Jr.

The nomination provoked a dispute between Rantoul and Benjamin F. Hallett, who supported Cabot and was in competition with Rantoul for the position of United States Attorney.

[4] Rantoul went on to lose to Whig incumbent Leverett Saltonstall I with a significant write-in vote for Cabot.

[5] Rantoul claimed these votes were cast by Gloucester fishermen returning from long months at sea who had been misinformed that Cabot was the Democratic nominee by "disorganizers.