Everton have broken their transfer record to sign Belgian midfielder Marouane
Fellaini for an initial £15million from Standard Liege.
The 20-year-old has signed a five-year deal, with the Toffees confirming the fee will rise throughout that time.
The deal was completed by chairman Bill Kenwright and manager David Moyes leading up to the midnight transfer deadline and announced in the early hours.
Acting chief executive Robert Elstone told the club website: 'This is fantastic news for everyone connected with the club.
'We have signed one of European football's most exciting prospects, who will have a huge part to play at Everton over the next five years.
'I spoke with Bill Kenwright and David Moyes shortly after concluding the deal and they are delighted we have managed to secure his services.
'It came late on, like a lot of the big deals in the Premier League, but he's with us and we look forward to welcoming him to Goodison.'
Fellaini joined Liege - Everton's forthcoming opponents in the first round of the UEFA Cup - two years ago and made 84 appearances for the Belgian champions, scoring 11 times.
He has also played 10 times for Belgium and represented his country at the Beijing Olympics, where he was sent off in the opening game for two yellow cards against Brazil.
Fellaini's arrival at Goodison Park follows those of keeper Carlo Nash, who signed from Wigan, and Manchester United striker Louis Saha.