Currently the manager of Borussia Dortmund, Klopp coached his team to the Champions League final in 2013. He also delivered back-to-back Bundesliga titles in 2010/11 and 2011/12, despite Dortmund being in the financial shadow of Bayern Munich. All of that was achieved while playing a distinctive attractive style of football. After six years at the club, it could be time for the 46-year-old German to move on.
The former England manager has coached the likes of Real Madrid, AC Milan, Juventus and Roma. He now resides over the Russian national team who topped their group in qualification for the 2014 World Cup in Brazil to ensure they are at the biggest tournament of them all for the first time since 2002.
Louis van Gaal
Dutchman Van Gaal will be leading his national side at this year's World Cup in Brazil. He has taken charge of both Barcelona and Bayern Munich in the past and won the Champions League in 1995 with Ajax. In total, he has won over 60 per cent of his 780 games in management and he's made it very clear he covets a position in the Premier League. Most recently linked with Tottenham.
Sir Alex Ferguson
Considering he's at every game anyway, a switch from the stands back to the dug-out doesn't seem inconceivable for Sir Alex Ferguson (left). It'd certainly be a popular choice among fans having achieved so much success in his long time in charge. The winner of 13 Premier League titles, five FA Cups and two Champions League titles, if there's anyone who can succeed Ferguson, it's Ferguson.
Since returning for a second spell at Chelsea last summer, the Special One has been saying he wants to see out his career at Stamford Bridge. Yet prior to returning to west London, it was an open secret he coveted the Old Trafford hot seat. If United want to turn their fortunes around, no other manager can provide the kind of guarantees of success that Mourinho can.
Frank De Boer
Although his managerial experience is relatively small in comparison to other potentials, he has already shown he can win domestically. Since taking over at Ajax in 2010, in his first job as manager, De Boer has won the Eredivisie in three consecutive attempts, with his team currently well clear at the top of the league this season. Has been regularly linked with the biggest vacancies in Europe.
Winner of the Serie A manager of the year in 2011-12 and 2012-13 after leading Juventus to the title in those seasons, as well as a Champions League winners medal to his name as a player, Conte has pedigree. Since taking charge in Turin three years ago, the Italian has returned Juventus to the dominant force in Italy, with the club destined to win their third title in a row this term. That kind of dominance is exactly what United crave.
Simeone has been enjoying much success at Atletico Madrid - out of 132 games in charge of the Spanish side, he has only lost 22 times. It's a record that's seen the club win the Europa League and Super Cup, and against all odds challenge Real Madrid and Barcelona for La Liga title this season. He'd have to hope his history with David Beckham didn't count against him.
Despite a rather sudden and messy divorce from Swansea City earlier this year, Laudrup did show he was capable of managing at the highest level. He won the League Cup with the Welsh club, the first major trophy in the club's history, and he did it with a brand of football that won many plaudits. A legend as a player, the Dane has the gravitas for such a huge position as Manchester United manager.
Currently manager of QPR, Redknapp has often been a fan favourite across English football, winning manager of the year in 2009/10 as well as the FA Cup with Portsmouth in 2008. At one stage he looked a certainty to be the next England manager, only to lose out to Roy Hodgson.
If Manchester United were to choose from one of their own, they would have plenty of ex-players to pick from. Caretaker manager Ryan Giggs (left) would be a popular pick as he was already a player/coach with the current squad. Others in management who served as a player under Sir Alex Ferguson include Roy Keane, Ole Gunnar Solskjaer, both Neville brothers and Steve Bruce. Mark Hughes played for United along with Gordon Strachan and Laurent Blanc. While none of them have particularly overachieved in any of their positions, a former player is often a safe choice if the owners don't want to upset the fans.
David Moyes has been sacked by Manchester United – quickly leading to the question: who will replace him?
The former Everton manager was hand-picked by his predecessor Sir Alex Ferguson, but Moyes won't have been given that privilege.
After enduring a season which will yield no trophies and the loss of Champions League football, the Glazers will be on the look out for a manager that can quickly return the club to the top table.
With a huge transfer kitty understood to be at any manager's disposal this summer, and the prestige of managing the most successful club in English history, there is likely to be a long queue of interested candidates.
Here, we take a look at the contenders...
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