John Frederick Parker was one of the four men tasked with being President Abraham Lincoln's bodyguard on the night of his assassination.
In the Timeless Universe
John Frederick Parker is seen at a bar on April 14, 1865, boasting about his close relation to Abraham Lincoln. To prove his knowledge of Lincoln, he spouts the fact that Lincoln was a wrestler who only lost one fight out of three hundred. When pressed by the bartender, Parker reveals the fact that he is Lincoln's bodyguard. The bartender asks Parker why he isn't guarding Lincoln. Parker replies it is because he's in the building next door watching a play. Ironically, Parker is staying at the same bar as John Wilkes Booth, who is the assassin of Abraham Lincoln in the original timeline.
John Frederick Parker at Wikipedia