Karen Allen first came to people's attention in 1978 with a role in National Lampoon's Animal House, a move praised by some critics as the funniest movie since Mel Brooks' The Producers (or so says Roger Ebert) and damned by others as the movie that changed Hollywood for the worse (because it kicked off an era of scatological frat-boy comedies that catered to the "young, dumb male" demographic). Three short years later, she became an important part of cinematic history.
Karen Allen played Marion Ravenwood in 1981's Raiders of the Lost Ark. Marion was the smart, savvy girlfriend of Indiana Jones (Harrison Ford) and the daughter of his mentor in the field of archaeology. Ms. Allen reprised the role in 2008's Indiana Jones and the Crystal Skull, in which she and Indy rekindled their mutual romantic interest . . . and in which Indy found out that he was the father of her son. Indy confessed to Marion that he'd dallied with several women, all of whom had one common flaw: "They weren't you." :-)
Not too many people liked Indiana Jones and the Crystal Skull, but I did. (Spoiler alert: Indy and Marion marry at the end.) Nevertheless, Karen Allen has this distinction going for her - she's the only lead actress to appear in two Indiana Jones movies.
Her various movie roles in between the first and (presumably) last Indiana Jones movies include Jenny Hayden in Starman, in which she befriends an alien from another planet (played by Jeff Bridges), Claire Phillips in Scrooged, the 1988 adaptation of "A Christmas Carol" (opposite Bill Murray) and Laura in the 1987 film adaptation of Tennessee Williams' The Glass Menagerie (directed by Paul Newman). She also a played a member of a yacht crew in 2000's The Perfect Storm.
Of all the actresses who played Indiana Jones' love interests, Karen Allen has had the most distinguished career. Because, like Marion Ravenwood, she has staying power. :-)