Silas Henry Harrison Clark (October 17, 1836 – June 1, 1900) was an American railroad executive.

[1] He moved to the Union Pacific Railroad in 1867 and rose through the ranks to eventually become its general manager,[1] working on behalf of wealthy financier Jay Gould, who controlled the line.

[1] In November 1886, Clark was appointed 1st Vice President and General Manager of the Missouri Pacific Railroad,[1] a road also controlled by Gould.

[1] He was also named the General Manager of the Union Pacific in December 1890, holding this dual post until February 1, 1893.

[1] On April 27, 1892, Clark was named President of the Union Pacific, replacing the recently deceased Sidney Dillon.