Paul Cullen has left his role as director of rugby at Widnes after four seasons with the Super League club.
Becoming director of rugby, he ushered the club into a new era as they took their place back in the top flight after a seven-year absence.
"I have enjoyed my time at Widnes and the time is now right for me to move on," said Cullen.
He told the club website: "I hope I have played my part in a revolution and it is now time for the Vikings to evolve.
"I believe that my objectives have been met, which were to win a trophy, win a licence, change from part-time to full-time professionalism and to deliver Super League to the supporters of the Widnes Vikings.
"There are exciting times and significant challenges ahead for Widnes and I wish all at the Vikings good luck for their future."