Gladys Presley was Presley's incredibly supportive mother. As the musician was growing up, he was close with his mother. "My mama never let me out of her sight. I couldn't go down to the creek with the other kids," Elvis once said about her (via The Express). As Presley grew more famous over time, she had a difficult time acclimating to his stardom. This led Gladys to drink heavily and use diet pills, which led to her death in 1958. According to Smooth Radio, she died from a heart attack, though liver failure from frequent alcohol use was also a factor that led to her death.