Former NRL and New Zealand Kiwis superstar Benji Marshall has revealed he doesn't know who his father is.

Formerly a personal secret, Marshall made the revelation on Channel 9's Celebrity Apprentice, which will conclude this evening.

In a segment of the show where the remaining contestants were asked to pitch a TV series idea to the streaming service Stan, Marshall's pitch was centred around the story he has never told.

"This is a story that I have never told," Marshall began.

"I have never ever talked about this publically. I have never ever talked about this because it means so much to me."

After playing footage of him playing for the Tigers during the famous 2005 premiership season, for which Marshall was one of the game's best players and developed much of his reputation, he revealed that wasn't the "real" him.

"That's the Benji Marshall that everyone else sees. The Benji Marshall that everyone thinks they know," he continued.

"300 games in the NRL, all these big moves, fancy steps, flick passes, you name it"

"That's not the real me. You know how I know that? Because I don't even know the real me.

"There is a half of me missing that I haven't found out about. I don't know my real dad. I don't know my culture. I don't know my nationality.

"Who am I?"

Marshall revealed he still doesn't know who his father is to this day, before pitching a six-part docuseries to "find out who he is."

Fans instantly supported the concept.

Marshall is currently working in NRL media with Fox Sports and is also still with the Tigers as an ambassador, while also assisting the club's pathways systems.