Warnock comes out of retirement to take on Huddersfield job
The 74-year-old announced his retirement last April, five months after leaving Middlesbrough.
Warnock is now back in the dugout for the 18th permanent position of his managerial career, with this his second spell in charge of Huddersfield.
He returns to the club almost 30 years after his first stint, during which time he earned the Terriers' promotion to the second tier via the play-offs in the 1994-95 campaign.
"I'm really excited about this challenge," Warnock told Huddersfield's official website.
"My first spell at Huddersfield Town had everything; we went to Wembley twice, moved into the new stadium, and really built the club from nothing. It was a special time.
"I'm coming back to help the club, but also [chairman] Dean Hoyle. I know what he has done behind the scenes and I've always had a lot of time for him.
"I've looked at the fixtures and we've got some fantastic games to come. I want to come back and put smiles on faces."
At the age of 74 years and 74 days, Warnock is 10 years older than the next-oldest manager in England's top four tiers – recently appointed Blackpool boss Mick McCarthy.
Warnock, whose coaching career started with Gainsborough Trinity in 1980, has managed 1,599 games in the top four tiers of English football, including the Premier League.
That is just two short of equalling the all-time record held by former Crewe Alexandra manager Dario Gradi.
His longest spell came at Sheffield United, where he managed for 388 games across eight years at the helm.
Huddersfield are one point from safety in the Championship relegation zone and travel to Stoke City in Warnock's first game back in charge on Wednesday.