Karen Jane Allen (Browne)

Karen started out doing period pieces including National Lampoon's Animal House, The Wanderers and A Small Circle of Friends.
Then she appeared in the genre classic Raiders of the Lost Ark (technically a period piece since it was set in 1936).
Karen moved on to performing on Broadway and off-Broadway, with occasional film and tv work, until Challenger where she met her future husband, Kale Brown, with whom she had a son.
In order to have more time with her son, she restricted her film / tv work to minor roles, mostly in East Coast-based projects like the Law & Order franchise and the film The Perfect Storm.
Karen also turned her longtime hobby, knitting, into a full-time business with both a brick and mortar storefront and website, and teaches acting at a local college.
She, thankfully, found time to reprise her role as Marion Ravenwood in Indiana Jones and the Kingdom of the Crystal Skull.
I'm looking forward to her next appearance, wherever it is!
Note: though it's not genre, if you're a Karen Allen fan, you'll want to see Until September. Trust me.

Genre appearances include...
Ghost in the Machine aka Deadly Terror (Terry Munroe)
Challenger (Christa McAuliffe)
[Not "sci-fi", but "sci-fact", and IMHO, well worthy of inclusion]
Secret Weapon (Ruth)
BackFire (Mara McAndrew)
Scrooged (Claire)
Ripper [VG] (Dr. Claire Burton)
Terminus (Gus)
Voyage aka Cruise of Fear (Catherine Norvell aka Kit)
Starman [1984]
(Jenny Hayden / performer: "All I Have to Do Is Dream")
Raiders of the Lost Ark aka
Indiana Jones and the Raiders of the Lost Ark /
Indiana Jones and the Kingdom of the Crystal Skull
(Marion Ravenwood)
Alfred Hitchcock Presents "The Creeper"

Check out...
Karen Allen Fiber Arts
Karen Allen: an ACME Page (FanPage)

Other actresses to play Jenny Hayden aka Karen Iseley include...

Erin Gray in Starman [1986]

Caryn Elaine Johnson

One of only three actresses* with an Oscar for an appearance in a genre film (1990's fantasy Ghost), Whoopi has an amazing list of genre credits in both tv and film.
Extremely talented, she can do everything (writing / producing / performing) except singing!

Genre appearances include...
Stream [webcast] (Jodi)
Life on Mars "Things to Do in New York When You Think You're Dead" (Brother Lovebutter)
Pinnochio 3000 (Cybernia)
A Knight in Camelot (Dr Vivien Morgan)
Golden Dreams (Calafia, the Queen of California / Narrator)
MonkeyBone (Death)
Magical Legend of the Leprechauns (Grand Banshee)
Alice in Wonderland (Cheshire Cat)
Rudolph the Red-Nosed Raindeer; The Movie (Stormella, The Evil Ice Queen)
A Christmas Carol [1997] (Spirit of Christmas Present)
Theodore Rex (Katie Coltrane)
Fatal Beauty (Rita Rizolli)
Rodgers & Hammerstein's Cinderella [1997] (Queen Constantina)
The Lion King / The Lion King 1 1/2 (Shenzi the Hyena)
Star Trek: the Next Generation / Star Trek: Generations / Star Trek: Nemesis (Guinan)
Ghost (Oda Mae Brown)
Captain Planet & the Planeteers (Gaia / Mother Earth)
Defenders of Dynatron City (Ms. Megawatt)

Check out...
Whoopi's personal blog
A FanPage

(*Josephine Hull won the Oscar in 1950 for the fantasy Harvey, and Ruth Gordon won in 1968 for the horror tale Rosemary's Baby!)

Shenzi has also been played by Tress MacNeille in Timon & Pumba.
Gaia has also been played by Margot Kidder in The New Adventures of Captain Planet
The Queen in previous versions of Rogers & Hammerstein's Cinderella has been played by Ginger Rogers [1965] and Dorothy Stickney [1957]