Marcal, John Ruddy and Romain Saiss will leave Wolves at the end of the 2021-22 campaign.
The club are in talks with Joao Moutinho, whose current agreement also expires this summer.
Saiss made more than 200 appearances in all competitions for Wolves.
“The moment I feared the most has come…” Saiss said on Instagram.
“The moment to say goodbye to you after 6 wonderful years with you.
“It was an honour and a privilege to wear these colours and to contribute to the success and renewal of this club.
“I have met exceptional people over these six years, always looking out for me and my family.
“Thanks to the fans for your support despite the ups and downs, you’ve always been behind me.
“Thank you to the various people working at the club for your kindness on a daily basis.
“Thank you to the various technical and medical staff for your work, for having been an important part of our success.
“Finally, thank you to all the players that I consider as family. A wardrobe of exceptional men that I will never forget.”
Ruddy has spent the last five seasons at Watford, while Marcal has played 32 times in the two years since his move from Lyon.