Watford have signed West Ham United full-back Jeremy Ngakia on the same day as seven players left Vicarage Road.
The 19-year-old was out of contract at the Hammers, having made five Premier League starts, and joins the Championship side on an unspecified contract.
Meanwhile, Cucho Hernandez, Dimitri Foulquier, Matheus Santana, Kwasi Sibo, Juergen Elitim, Jaime Alvarado and Williams Velasquez will not be at Vicarage Road next season.
Hernandez has joined Getafe on a season-long loan, having spent the last two years out on loan, while the Spanish club have exercised the option to turn Foulquier's loan into a permanent deal.
Brazilian midfielder Santana is also heading to Spain to join Recreativo de Huelva on a permanent deal, while Sibo will stay at UD Ibiza for a second season on loan.
Elitim has joined Ponferradina, Alvarado has signed for Brazilian outfit Club Athletico Paranaense and Velasquez is staying at MLS side Portland Timbers.
