Bart Bass
Even in season 1 Chuck has had a very strained relationship with his father. Chuck just wanted his approval but Bart never gave it to him. In season 2 Bart faked a car accident and his death, and Chuck's world almost fell apart. In season 3 Chuck saw a woman named Elizabeth Fisher put flowers on his father's grave and he realized that she was his mother. Bart always told him that his mother died in childbirth. In season 5, it is revealed that Bart is actually alive and just faked his death. That is when Bart tries to kill Blair and Chuck, but he ends up dying for real in season 6 episode 9.
Here you can watch the hospital scene that was about the Anniversary of Bart's fake deat
Here you can watch the hospital scene that was about the Anniversary of Bart's fake deat