Born to William West Toole Jr. and Dorothy Geraldine Niland, Annette began acting at a very young age, doing guest appearances in shows such as My Three Sons (1960), The Virginian (1962), Gunsmoke (1955), and The Partridge Family (1970).

Her first major role was as Robby Benson's tutor/girlfriend in the college basketball opus One on One in 1977. In 1981, she starred in the HBO onstage production of Vanities. Later on in 1982, she played Nick Nolte's loyal girlfriend in 48 Hours. In the same year, she appeared opposite Nastassja Kinski in Cat People. 1983 saw her play the part of Lana Lang in Superman III opposite Christopher Reeve. In 1985 she co-starred with Barry Manilow in the CBS television movie Copacabana. O'Toole played Lola Lamarr to Manilow's Tony Starr. In 1990 she played the adult Beverly Marsh in the horror miniseries based on the Stephen King novel It.

She had recurring roles on the television shows Nash Bridges (1996) and The Huntress (2000). She guest-starred on Boy Meets World in 1999. She has also performed in a number of successful theater productions. In October 2001, she returned to the Superman mythos in the role of Martha Kent, Clark Kent/Superman's mother, in the television series Smallville, a role she played until the Season 6 finale. She is thus the only actress ever to play both Superman's girlfriend and Superman's mother.

O'Toole has been married to actor Michael McKean since 1999, and in 2003 the duo were nominated for the Academy Award for Best Song for A Kiss at the End of the Rainbow, a love duet that they had written for the movie A Mighty Wind. O'Toole and McKean guest-starred together in an episode of Law & Order as a wealthy married couple accused of murder. McKean also became part of the Superman mythos when he guest starred on Smallville playing Perry White.

On July 7th 2007 O'Toole appeared as a backing singer for her husband's fictional band Spinal Tap at the London leg of the Live Earth concerts.

Source: wikipedia.org