10. Asmir Begovic – Portsmouth to Stoke, 2010 (£3m)
After a handful of Premier League appearances for Portsmouth and string of loan spells in England's lower leagues, the Bosnian signed for Stoke in the 2010 January transfer window and grew in stature from there. While he conceded five goals against Chelsea on debut two months after signing, Begovic improved and eventually established himself as one of the best young goalkeepers in the league.
In November 2013 he also set a Guinness World Record for the longest goal scored, getting on the scoresheet from almost the full length of the pitch against Southampton.
In five-and-a-half seasons at Stoke, Begovic made 173 appearances and kept 50 clean sheets, before departing for Chelsea in summer 2015.
9. Jermain Defoe – West Ham to Tottenham, 2004 (£7m, part exchange)
Defoe enjoyed two stints at White Hart Lane, with a spell with Portsmouth sandwiched in between.
In his first (a deal where Bobby Zamora went the other way), the English striker made 177 appearances and scored 64 times, and was named the Spurs' player of the year for 2004 having only joined in January of that season.
Tottenham at that time were still considered a mid-table club, but with the help of Defoe’s contributions they eventually started to knock on the door for qualification into Europe.
8. Marouane Fellaini – Standard Liege to Everton, 2008 (£15m)
Fellaini made an instant impact in England after joining Everton in September 2008 – not because of his unique hairstyle or flailing elbows, but thanks to his ability to cause chaos inside opposition boxes bombing forward from midfield.
READ MORE: The 10 most bizarre deadline day stories
READ MORE: The 10 worst January transfers ever
He was named the club’s young player of the year in his debut campaign and gradually established himself at Premier League level under David Moyes’s tutelage. In five years in the blue half of Merseyside, he made 177 appearances and scored 33 times.
It wasn’t a surprise, then, when Moyes brought him to Old Trafford via another deadline-day signing in 2013. That time it cost him almost £28m, though – and the wrath of Manchester United fans.
7. Robbie Keane – Leeds to Tottenham, 2002 (£7m)
It's fair to say that Leeds probably should have asked a bigger fee from Tottenham for Keane. At just £7m, the Irish striker was an absolute steal – not least as he'd cost Coventry £6m in 1999, Inter Milan £13m a season later, and then Leeds £12m in May 2001.
Keane spent nine years at White Hart Lane over two spells between 2002 and 2011, broken up by a six-month stint with Liverpool (from which Spurs received £19m), plus loans at Celtic and West Ham. In 303 appearances he scored 122 goals – enough for him to rank among the top 10 goalscorers in Spurs history... until Harry Kane came along.
That he was named Spurs’ player of the season three times – including in his debut campaign – outlines the Irishman's level of performance. A pity, though, that he only lifted a solitary League Cup title in his time there.
6. Carlos Tevez/Javier Mascherano – Corinthians to West Ham, 2006 (Undisc.)
Jaws dropped when West Ham signed the Argentine duo, who arrived at Upton Park with pedigree and promise.
Mascherano, then 22, struggled to establish himself (famously falling behind Hayden Mullins in the pecking order) and left on loan to Liverpool in January 2007 – although he netted West Ham a huge £18.5m when the move was made permanent at the end of that season.
Tevez, on the other hand, almost singlehandedly saved the Hammers from relegation. With 10 games to go and the east Londoners languishing in the bottom three, he scored seven times – including the all-important winner against Manchester United at Old Trafford on the final day of the season – in helping West Ham claim seven victories and a finish three points above the drop zone.
5. Ashley Cole – Arsenal to Chelsea, 2006 (£5m)
Cole can be considered one of the greatest bargains in Chelsea’s history, having moved to Stamford Bridge for just £5m. Granted, the Blues had to give up William Gallas as part of the deal, but what Cole helped the club achieve more than proved his worth.
In eight years at Stamford Bridge, the ex-England international won as many major honours, including one Premier League crown, four FA Cups and the 2012 Champions League – Chelsea’s first ever triumph in the competition. In total, he made 338 appearances and scored seven times.
4. Hugo Lloris – Lyon to Tottenham, 2012 (£8m)
Lloris was once touted as a potential rival to Manuel Neuer as the best goalkeeper in the world, so it was surprising when Tottenham managed to sign him for a relatively cheap £8m in 2012.
Since then, the French goalkeeper has become captain of both club and country, leading from the back with command and consistency – as he demonstrated during France's victorious World Cup campaign.
3. Claude Makelele – Real Madrid to Chelsea, 2003 (£16m)
Makelele was often referred to as the most important player within a Real Madrid team filled with Galacticos, to the point that even the usually-reserved Zinedine Zidane aired his disgruntlement when his compatriot was sold to Chelsea in 2003.
In total, he made 217 appearances for the Blues and became an essential element of Jose Mourinho’s dominant team that claimed back-to-back league titles in 2005 and 2006 – so much so that a position on the pitch was named in his honour.
In his final season in London, he helped guide Chelsea (then under Avram Grant) into their first ever Champions League final... where they lost on penalties to Manchester United.
2. Luis Suarez – Ajax to Liverpool, 2010 (£22.8m)
Forget the controversies for a second: Suarez's signing was one of the greatest deals in Liverpool's history, at a time when they were making many bad ones. In four seasons on Merseyside, the Uruguayan scored 82 goals in 133 appearances and earned cult hero status, helping Liverpool fans move on swiftly from Fernando Torres.
While he couldn't quite guide the Reds to the title – they fell just short in Suarez’s last season of 2013/14 – he did help them win the League Cup in 2012 and earned a host of individual honours, including Liverpool Player of the Season twice and the PFA Player of the Year in 2014.
His eventual transfer to Barcelona also netted Liverpool a hefty profit in the region of £42m.
1. Wayne Rooney – Everton to Man United, 2004 (£20m)
The images of Rooney as a teenage tyro are long faded, but for a decade he was essential to Manchester United's cause as they dominated the Premier League and triumphed on the continent.
By the time of his return to first club Everton in 2017, Rooney had 253 goals at Old Trafford – making him the club's all time record goalscorer – and 11 major honours to his name.
He was also named in the PFA Team of the Year three times, was the PFA Player’s Player of the Year in 2009/10, PFA Fans’ Player of the Year twice and the PFA Young Player of the Year twice. A bona fide Stretford legend.