The Simpsons creator Matt Groening is mourning the death of his mother, who inspired him to create his cartoon family matriarch Marge Simpson. Margaret Groening passed away in her sleep on 22 April (13) in her hometown of Portland, Oregon. She was 94. Her animator son famously based his blue-haired character on his mum. Groening's cartoonist dad Homer - the inspiration for Bart Simpson's father - died in 1996.