Jacob Senewell Yost (July 29, 1801 – March 7, 1872) was an American politician who represented Pennsylvania in the United States House of Representatives.
Yost was born in Pottsgrove Township, Pennsylvania, near Pottstown, Pennsylvania. He attended the common schools and Fourth Street Academy in Philadelphia. He engaged in agricultural pursuits and served as publisher and editor of the La Fayette Aurora in La Fayette, Pennsylvania.
He was a member of the Pennsylvania State House of Representatives from 1836 to 1839. Yost was elected as a Democrat to the Twenty-Eighth and Twenty-Ninth Congresses, serving from 1843 to 1847. He resumed a political position as the U.S. Marshal for the Eastern District of Pennsylvania by appointment of President James Buchanan, serving from 1857 until his resignation in 1860.
Afterward he continued his agricultural pursuits until his death in Pottstown, Pennsylvania, at the age of 70. He was interred in Edgewood Cemetery in Pottstown, Pennsylvania.