Stanley raved about the "Two Tickets to Paradise" singer's debut album, which he loved, on Twitter and offered up thoughts and prayers to the late star's family.
"EDDIE MONEY RIP," he wrote. "So sad to hear of his passing... A fine singer through the years."
Meanwhile, Hagar issued a statement to Billboard, writing, "I watched Eddie for the last year struggle with his wonderful close family right there by his side doing anything and everything they could possibly do. He put up a good fight. And his songs will play on forever."
Fellow rocker Marx took to Twitter and called Money, "Such a sweetheart."
"Saw him in January at our benefit for the Malibu fires/Borderline shooting victims and hadn't seen him in years," he added. "He gave me a big hug and immediately, while still hugging me, whispered a dirty joke in my ear...."
"Metallica played sort of like a special show at the Palladium in L.A. right after they appeared that night on the Grammys with Lady GaGa, and I was up in the VIP section watching Metallica and Eddie Money was up there," he recalls, "and I was just hanging out with him, talking, and he was like super nice and really funny..."
"He had that very distinctive voice. And he was just one bad joke after another after another. He was really super cool."