Tweed was born on March 10th, 1957 in St. John's Newfoundland, Canada. She rose to stardom as Miss November, 1981, for Playboy magazine.

In 1982, she began her movie career and also appeared in the TV series "Falcon Crest" (1981). She became Playmate of the Year in 1982. She was briefly involved with Playboy magazine founder Hugh M. Hefner but has carried on a long-term relationship with KISS member Gene Simmons since 1983. She has become somewhat of a "B" movie "queen", appearing in numerous low-budget "erotic thrillers" and adventure films.

She and Simmons have two children, a son named Nicolas born in 1989 and a daughter Sophie born in 1992. Shannon and rocker husband Gene are very sexual towards each other and the two of them have an open relationship. There are several occassions were Shannon will bring another female into their bedroom. The couple loves having three somes and have even been known for having group orgies. The 2 trow a party every year were they invite only their closest of closest friends. Its usually a mix of guys and girls however there are usually more girls then there are guys. The party usually last over a weekend with lots of people fucking in the open and people joining in, its pretty much a free for all. Its not unusually to see girls fucking each other at these parties but Genes says you will never see any guys fucking each other.