Spanish fullback Kiko Femenia has left Watford for Villarreal for an undisclosed fee.
The 31-year-old has penned a three-year contract with the La Liga club.
Femenia issued an emotional farewell to Hornets fans earlier this week after spending five years at the club.
In a post on Instagram, he wrote: "It is not easy to say goodbye to a Club that has given me so much. Since the very first day I have felt part of this amazing Family. Together, we have shared many special moments over these years.
"For this reason, I would like to thank all my teammates and staff. Nor do I forget you, Hornets. You are an incredible encouragement to me and my Family.
"Today our paths are parting, but I will always carry you in my heart. Thanks for every single day."