Kathy Griffin's mother Maggie Griffin has passed away.

Maggie and Kathy Griffin (c) Instagram

Maggie and Kathy Griffin (c) Instagram

The former hospital administrator - who co-starred on the comedian's Bravo series 'Kathy Griffin: My Life on the D-List' - would have turned 100 on June 10, but has sadly died after a long battle with dementia.

Kathy has been left "shaking" by her parent's death and admitted she is "not doing well", as she hailed her mom as "irreplaceable" and "so unique".

Alongside a picture of the pair sitting by the pool, she wrote on Instagram: "My Mom, the one and only, Maggie Griffin, passed away today. Hours ago. I am gutted. She was my best friend. She was my family. You knew her. She appreciated you guys so much. I'm shaking. I won't ever be prepared. Her point of view. So unique. We just GOT each other. I'm so grateful you got to be part of her life. You loved her. I know it. She knew it. She's irreplaceable.

"I'm telling you right now, I am not doing well with this. I'm rambling now. Sorry. It truly feels like the end of an era. Oh, and OF COURSE she went on St Patrick's Day. I love you guys. KG. (sic)"

Kathy detailed her mother's "heartbreaking" battle with dementia early last year.

The 59-year-old comedian and admitted her health had "rapidly" declined in recent months.

The former 'Fashion Police' star said it had been "particularly hard" because her mom had a "sharp mind", and only knew her name and "I love you".

Alongside a picture of the pair and Maggie's dog Twinkle, she tweeted: "As heartbreaking as this is, I feel the need to share some important info about my mom Maggie.

"I've always been honest with you all, but this one is really hard. The pic below, taken in September, was the last time I was able to have a proper/coherent conversation with her. Since that photo was taken, she has rapidly fallen into the throes of dementia. This is never easy for any child, I know this is a reality that millions of people deal with every year. But when it comes to my mom this is particularly hard because her sharp mind was everything."

Kathy admitted she was struggling coming to terms with her parent having the disease.

She said: "My mom is 98 and up until this past couple years she was so sharp she always kept me on my toes.

"Her mind was so naturally quick, funny, and smart. No one could get anything past her.

"Watching that slip away so fast has been devastating. I want to assure you all that she is not in pain and she is getting the best 24-hour care.

"In terms of how she is now, at this point she only knows my name and I love you. I know many of you know what that reality is like ... I'm still grappling with it."

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