Lee Najjar — best known to “The Real Housewives of Atlanta” fans as Kim Zolciak’s elusive “Big Poppa” sugar daddy — has died at 68.

The wealthy Atlanta real estate investor passed away Saturday, April 18 — tragic news confirmed by his daughter Katelin via a slate of IG Story pictures of them together and an emotional tribute. Lee’s cause of death is unknown.

The Miami-Dade Medical Examiner also confirmed his death to TMZ.

Najjar became a notorious off-camera figure during the early seasons of ‘RHOA’ — as the mystery man bankrolling Zolciak’s luxe lifestyle — all while he was still reportedly married to another woman.

He and his wife shared two children — Katelin and Jeremy Najjar.

“Big Poppa” was never fully shown on camera, but his presence loomed large … fueling one of the show’s juiciest early storylines and helping cement ‘Housewives’ as must-watch TV.

Kim said back in 2009, when their romance ended, “He will always be the love of my life, but it’s time for me to move on” … and it wasn’t long after that his identity became public.

He was 68.