Allen Halliwell

Allen Halliwell was a mortal who lived in San Francisco. He was the first husband of Penelope Johnson and father of Patricia Halliwell, and thus the grandfather of the Charmed Ones. His parents were Isabelle and William Halliwell and stepson to Matthew Halliwell, William's brother.

Early Life
Penny married Allen sometime in the 1940s. In 1950, he and his wife Penny had a daughter, Patricia.

By the late 1960s, Allen had come in contact with several hippies and led Penny into that lifestyle. They eventually became important leaders in San Francisco's community of hippie-witches.

Death
In January 1967, Allen helped Penny plan a magical be-in at the manor so they could tap into the power of the Nexus. Allen and Penny didn't know that Penny's best friend, Robin, was really an evil witch who planned to slaughter all the attendees with her warlock partner Nigel.

Allen noticed Robin was acting strangely and followed her into the attic. He found her chanting a spell to unleash evil in the manor. Allen tried to talk her into giving up evil, but Robin replied by killing him with a fireball. Penny flew into a rage at seeing Allen's body and killed Robin on the spot. Although painful, Allen's death made Penny the relentless demon and warlock hunter that she was while raising her granddaughters.

Witchstock
In 2004, Paige was transported back to 1967 when she put on a pair of Grams' old go-go boots. She walked in on Robin just as she was about to throw a fireball at Allen. Robin ended up dying from one of her own fireballs after Paige knocked her off her feet, thus altering the timeline.

Even after finding out what Robin and Nigel were planning, Penny didn't want to use her telekinetic abilities for fighting because of her strong pacifist beliefs. Later, Nigel blinked back in and tried to kill Penny and Piper, but Allen pushed them out of the way. He was hit by a fireball and died.

Penny was so distraught that she planned on binding her powers, but Piper, Phoebe and Paige convinced her that it was more than acceptable to fight for someone she loved. Penny then vanquished Nigel and became the person she was meant to be, thus correcting the timeline.