Marvel continues to fill the ranks of its Avengers.

Actress Cobie Smulders, best known as Robin Scherbatsky on CBS’s Emmy-winning comedy “How I Met Your Mother,” has joined the cast of director Joss Whedon's superhero ensemble "The Avengers," slated to hit theaters next summer.

Smulders will play Maria Hill, an agent for the quasi-military espionage agency known as S.H.I.E.L.D and led by Nick Fury (Samuel L. Jackson). Like Jackson, Smulders is likely to be contracted for a nine-movie deal that will allow the character to cross-over into multiple Marvel films.

In the comics, Hill is known for her forceful personality and a hard edge similar to that of Fury. The character ultimately takes over S.H.I.E.L.D. and features prominently in the popular “Civil War” and “Secret Invasion” storylines.

The big-budget action film will mark a change of pace for the Canadian actress who has largely worked in comedies and television appearances.

In addition to her work on “Mother,” her television appearances include “The L Word,” “Smallville,” “Andromeda,” and “Tru Calling.”

Prior to settling on Smulders, Marvel recently conducted screen tests with several actresses on the short list to play Hill. They included Morena Baccarin ("V", "Firefly"), Jessica Lucas ("Cloverfield"), and Mary Elizabeth Winstead ("Scott Pilgrim vs. The World").

The addition of Smulders helps even the gender odds in the male-skewed cast of "The Avengers."

Alongside Jackson and Smulders, the film will see Robert Downey Jr, Scarlett Johansson and Clark Gregg reprise their “Iron Man” roles as Tony Stark/Iron Man, Black Widow and Agent Coulson, respectively.

Chris Hemsworth and Chris Evans, who will appear in theaters this summer as Thor and Captain America, respectively, will also star, and Mark Ruffalo will assume the role of Bruce Banner/The Incredible Hulk, last played onscreen by Edward Norton.

Rounding out the cast is Academy Award nominee Jeremy Renner (“The Town,” “The Hurt Locker”) as Hawkeye.

“The Avengers” will hit theaters on May 4, 2012.

“How I Met Your Mother” airs Mondays at 8 p.m. EST on CBS.