A half-naked dead body washed ashore in a ritzy Hamptons enclave this week, leaving witnesses stunned at the “ghastly” sight.

The body of Keith Viagas, 63, was spotted Monday morning by two kayakers lying face down on the shoreline of Sag Harbor Cove, in a wealthy village where celebrities like Billy Joel and Richard Gere own homes.

“He was nude apart from a black shirt around his neck, black socks or swim booties on,” one witness told Page Six.

“It was a ghastly sight to stumble across on a beautiful August summer morning.”

The cause of death will be determined by the Suffolk County Medical Examiner’s office, but cops don’t suspect foul play.

“He’s a long-term resident but he was not reported missing because he would commonly go away for a couple of days then return,” Southampton Police Lt. Susan C. Ralph told The Post.

Sag Harbor has long been a getaway and home for wealthy New Yorkers and celebrities including “The View” co-host Joy Behar, who has a $7.13 million home, Real Housewives Jill Zarin and Luann de Lesseps, disgraced newsman Matt Lauer and crooner Jimmy Buffet. Artists including artists Eric Fischl and April Gornik have also lived there.

Also nearby is the house Khloe and Kourtney Kardashian rented for their summer-spin off “Kourtney & Khloé Take the Hamptons” in 2014.

The sisters opened a pop-up retail store, Dash, in Southampton Village for the season, and sisters Kim Kardashian, Kendall Jenner and Kylie Jenner, as well as matriarch Kris Jenner, visited the North Sea abode.

It was later rented by pop star Rihanna for a whopping $415,000 a month, The Post revealed.