Millwall have signed Japhet Tanganga from Tottenham Hotspur on a permanent transfer.
The 25-year-old made 18 appearances on loan at The Den last season as the Lions finished 13th in the Championship.
Tanganga has signed a "long-term" deal, external after his Tottenham contract expired this summer.
He made 50 senior appearances for Spurs after coming through the club's academy.
Tanganga is Millwall's second summer signing, following the arrival of Macaulay Langstaff from Notts County on Monday.