In Lost, what was the name of Jack Shephard’s father?

Jack Shephard’s father in Lost was named Christian Shephard.

Christian was a prominent spinal surgeon and the father of Jack and Claire Littleton. His death before the crash is central to the pilot: Jack travels on Oceanic Flight 815 while accompanying Christian’s coffin back to the United States.

The character appears in flashbacks and later becomes connected to the island’s supernatural mysteries. Jack repeatedly sees what appears to be Christian on the island, creating uncertainty about whether the figure is a ghost, an apparition, or another force using Christian’s appearance.

Christian is played by John Terry. A common mix-up is treating him as only Jack’s father; later revelations establish that Claire is also his daughter, making Jack and Claire half-siblings.