Meredith was born and raised in St. Charles, Missouri. Growing up, she developed a strong love for pop music, with Ego later claiming that she memorized every song that came over the radio. She eventually met Ego with whom she fell in love. In 1980, Ego drove her out to a forest where he showed her a seedling he had planted, claiming that it would soon spread everywhere across Earth.
Later that year, Meredith was impregnated by Ego and gave birth to a son she named Peter. Ego was soon forced to return to his planet, in order to replenish his life force. Meredith raised Peter by herself and gave him a Walkman with a mixtape of her favorite songs, which Peter adamantly protected from then on. She called him her little "Star-Lord", which an adult Peter adopted as his outlaw name.
Ego returned three times to visit Meredith Quill. Fearing that he was becoming too attached to her and becoming unfocused in his mission, Ego decided to kill her, although he was not without remorse for it. He used his power to cause an inoperable malignancy to develop in her brain, dooming her to die of brain cancer.
Meredith died of terminal cancer in 1988, when Peter was eight years old, but gave him a second mixtape of music just before passing. He did not open this second tape until many years later, after defending the planet Xandar as a member of the Guardians of the Galaxy. After taking hold of the Power Stone during the conclusion of the battle to prevent Ronan the Accuser from taking it back, Peter's body began to rip apart, causing him unbearable pain. He began hallucinating and saw an image of his dying mother asking him to take his hand. In reality, this was Gamora calling to him to take her hand so that they could share and absorb the stone's power.
A statue of Meredith Quill was built on Ego's planet. Peter Quill stated that his family back on Earth thought she was delusional due to her brain cancer when she claimed her husband was from the stars. Quill and Ego both got into a heated argument about why Ego never returned to see Meredith, to which Ego explained that his humanoid form must return to his planet regularly otherwise it would decay if he didn't return; most importantly, he could not stand Meredith's death, claiming Quill could not understand how this felt.
Ego grievously stated that, despite him making countless mistakes for eons, Quill was not one of them and he wished to be the father who bonded with his son, stating it was what Meredith wished for. He taught Quill to focus on his essence within the planet to harness energy to conjure up an energy ball, thus resulting in a bonding between father and son.
However, this all went downhill when Peter learned about Ego's true motives and that Ego was the one who put the tumor inside Meredith's head in the first place. Angered by this revelation and determined to avenge his mother's death, as well as to protect the planets Ego had visited from the Expansion, Peter arranged for Rocket Raccoon and Groot to plant a bomb inside Ego's core, destroying Ego for good.
- In the comics, Meredith Quill rescued the space prince J'son and fell in love with him. After his departure, she was killed by two Badoon soldiers, who were sent to kill their son Peter.