On November 12, Stan Lee, the co-creator of iconic Marvel Comic book characters like Spider-Man and Black Panther, passed away at the age of 95.

Celebrity news website TMZ reported that Lee, whose real was Stanley Martin Lieber, was rushed to Cedars-Sinai Medical Center after ambulances were called to his Hollywood Hills home that morning.

Failing health

At the time no cause of death was revealed, but Lee had been suffering from a slew of ailments, including pneumonia, impaired hearing, and vision problems.

In February, he was hospitalized for having an irregular heartbeat, but was released the next day.

That same month, Lee told TMZ that his hospitalization was due to aspiration pneumonia, which occurs when you inhale food or drink particles, vomit or saliva into the lungs.

A few months before his death, court documents revealed that his failing health and several canceled public appearances may not have only been a result of old age. Lee was allegedly a victim of elder abuse by his own manager Keya Morgan.

Los Angeles Police Department performed wellness checks on Lee, and in May, a court eventually granted him a temporary restraining order against Morgan.

Over the next few months, Lee appeared to have been on the mend, but his health troubles would eventually return in full force.

Cause of death

According to his death certificate, which was released this week by the Los Angeles Department of Health, Lee died from a cardiac arrest, respiratory, and congestive heart failure.

It appears as though the comic book legend never fully recovered from the bout of pneumonia he suffered earlier in the year.

This new information comes just about two weeks after Lee was laid to rest in a private funeral "in accordance to his final wishes."

"As we all continue to process our feelings of loss at the passing of a true legend, many are asking if there will be a memorial in Stan's honor," POW! Entertainment said in a statement. "Stan was always adamant that he did not want a large public funeral, and as such his family has conducted a private closed ceremony in accordance with his final wishes. Our thoughts and prayers continue to be with them."

Lee is survived by his daughter, Joan Celia "J.C." Lee and his brother Larry Lieber. His wife, also named Joan, died last year after 69 years of marriage.