Watford have signed Craig Cathcart from Sky Bet Championship rivals Blackpool.
Cathcart, a former Hornets loan player, has put pen to paper on a two-year deal at Vicarage Road after seeing his contract with the Seasiders expire.
The 25-year-old made 12 appearances for Watford under then-manager Malky Mackay in 2009 before his temporary spell at the club was cut short due to a knee injury.
He joined Blackpool the following summer, soon after their promotion to the Premier League, and has remained there since, making 117 appearances during his four-year stay.
Cathcart, who has 18 Northern Ireland caps, can play at centre-back or on the right-hand side of the defence.