Zachary Taylor (1784-1850), twelfth President of the United States, showed such little interest in politics that he never cast a vote in a presidential election until his own election in 1848.
Known by the nickname “Old Rough and Ready”, Taylor served with distinction as a military officer, but his presidency was a study in mediocrity.
He almost missed out on the nomination for the presidency due to one postage stamp. The official notice of his nomination by the Whig Party went unacknowledged for so long that party officials sent a delegation to look into the matter. They discovered the letter had not been delivered and was sitting in the post office’ Dead Letter Office, due to insufficient postage. (source)
Taylor died in 1850, likely due to cholera. Rumors persisted about an assassination, however, and in 1991 the deceased President’s body was exhumed with full military honors, and tested for arsenic poisoning. The tests revealed no evidence of foul play.