The Avengers

Marvel is conducting screen tests Friday for one of the final roles still looking to be cast in The Avengers, the all-star superhero ensemble being directed by Joss Whedon. Last night Samuel L. Jackson revealed on Late Night with Jimmy Fallon it is that of his "sidekick."

V star Morena Baccarin is on that list. Also said to be vying for the part are Jessica Lucas, Cobie Smulders and Mary Elizabeth Winstead, who are still negotiating their test deals for the part of a key member of the espionage agency run by Nick Fury, played in the Marvel movies by Jackson. Some earlier speculation pegged the role to be that of Avengers team member Janet van Dyne/the Wasp, but Marvel declined to comment.

The test deals for the role involve a nine-picture option, so whoever snags the role has a chance to be seen in subsequent Marvel movies. There is also a 30-day hold on the actresses.

Baccarin, repped by ICM and Seven Summits, may have an edge since the actress did star in Whedon’s short-lived sci-fi TV series Firefly and its subsequent film spinoff, Serenity.

Lucas, repped by Gersh and Thruline Entertainment, was one of the stars of Melrose Place, appears in TV’s Friends With Benefits and has a role in Big Momma’s House 3.

Smulders, repped by UTA and Roar, is best known for her work in CBS’ How I Met Your Mother.

Winstead, who played Ramona Flowers in Scott Pilgrim vs. the World, next stars in Universal’s The Thing, the remake of the 1982 John Carpenter horror movie. She is repped by CAA.

The casting of the female actress will serve to (slightly) even the gender odds in male-heavy cast. Scarlett Johansson (as the Black Widow) is the only notable female in a roll call that includes Robert Downey Jr. (Iron Man), Jackson (Nick Fury), Jeremy Renner (Hawkeye), Chris Evans (Captain America), Mark Ruffalo (Hulk) and Chris Hemsworth (Thor).