UPN staffers are mourning the loss of publicist Charles Barile, 49, who died Saturday while on vacation in San Felipe, Mexico.

Medical examiners have not yet determined the cause of death.

Barile’s sudden death stunned former and current colleagues at the net.

“He’s the guy who came in wearing a jacket, with a handkerchief in his coat pocket,” marveled one UPN colleague. “He was always warm, with a smile and a handshake. He was always the first guy out there to help you; everybody was his best friend.”

Barile joined UPN’s media relations department in 1999, working on programs such as “Buffy the Vampire Slayer” and “WWE Smackdown.”

“Charles was an incredibly talented and gifted professional whose contributions to UPN were innumerable,” said UPN senior VP of media relations Joanna Lowry. “But above and beyond that, Charles was a great friend and a class act. He left an indelible impression on everyone who had the pleasure of knowing him, and he will be greatly missed.”

Before UPN, Barile spent 10 years at NBC as director of talent relations. He also was a talent booker for Merv Griffin Prods. and a talent agent, starting out in the William Morris Agency mailroom.

Born and raised in Fresno, Barile received a bachelor of arts degree at UC Davis and attended UCLA film school. Separate from his job, Barile was an avid fan of anything having to do with the Kennedy clan.

“He revered the old Hollywood of Berle, Marx and Hope, yet could shmooze anybody from wrestlers to rappers,” said Paul McGuire, who hired Barile at UPN and now is senior VP at WB media relations.

Services will be held Thursday in Fresno; a memorial is being planned for later this month in L.A. Donations may be made in Barile’s memory to the UCLA Film & Television Archive, c/o Rosalee Sass, Box 951622, Los Angeles, 90045-1622.