Elizabeth Henstridge and Iain De Caestecker have joined Ming-Na and Clark Gregg in ABC's Marvel TV pilot.

ABC has found two more agents for its Joss Whedon pilot, S.H.I.E.L.D.

Elizabeth Henstridge and Iain De Caestecker have boarded the Marvel TV adaptation, The Hollywood Reporter has learned exclusively.

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The project from ABC Studios is based on Marvel Comics' secret intelligence organization that has appeared in countless titles including Iron Man, Captain America and The Ultimates since being introduced in the 1960s. The military law-enforcement agency's moniker stands for Strategic Hazard Intervention Espionage Logistic Directorate, which also has evolved over time in the comics.

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Henstridge will play science whiz Agent Gemma Simmons, while De Caestecker will play Agent Leo Fitz, a technology guru. The duo spend all their time together -- mostly bickering -- and are masters of their respective fields at a remarkably young age.

Henstridge and De Caestecker join the previously cast Ming-Na, who will play top-notch pilot and weapons expert Agent Melinda May, and Clark Gregg, who reprises his role from The Avengers as Agent Phil Coulson.

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Whedon is on board to co-pen the pilot alongside his brother Jed Whedon and Jed's wife Maurissa Tancharoen; the trio previously teamed on the three-part web series Dr. Horrible's Sing-Along Blog. Avengers and Buffy the Vampire Slayer mastermind Whedon will direct the pilot if his schedule permits.

Henstridge's credits include Hollyoaks and the J.J. Abrams and Mark Schwahn's Shelter pilot at The CW. She's repped by UTA and Evolution.

De Caestecker previously was the lead on a pair of BBC series: BAFTA winner The Fades and Young James Herriot, which earned him a best actor nomination at this weekend's Scottish BAFTA Awards. He next appears in the feature In Fear, with Alice Englert. He's repped by WME, Anonymous Content and Hamilton Hodell.

Email: Lesley.Goldberg@thr.com; Twitter: @Snoodit