John Tyler became President after W.H. Harrison’s death in 1841 but did not run in 1844. Millard Filmore became President after Z. Taylor’s death in 1850 but did not run in 1852. Andrew Johnson became President after A. Lincoln’s assassination in 1865 but did not run in 1868. Chester Arthur became President after J. Garfield’s assassination in 1881 but did not run in 1884. For those who put "Ford" in their guess, Ford did not become President when his predecessor died.