Marvel's "Agent Carter" will unveil the early secrets of S.H.I.E.L.D., known in 1946 as the Strategic Scientific Reserve, in its premiere season beginning on Tuesday, Jan. 6.

The latest Marvel TV show will debut eight episodes as "Agents of S.H.I.E.L.D." goes on an extended winter hiatus. "S.H.I.E.L.D." will return on Tuesday, March 3.

"Agent Carter" star Hayley Atwell made a guest-appearance in the season two premiere of "S.H.I.E.L.D." earlier this fall. She appeared in a flashback scene with her "Captain America: The First Avenger" co-stars Neal McDonough and Kenneth Choi.

Atwell's character Peggy Carter will also make a guest appearance in next summer's Marvel movie "Ant-Man," starring Paul Rudd and Michael Douglas. Her character will most likely appear in a scene with John Slattery's Howard Stark character, last seen in "Iron Man 2."

ABC released an early clip of the "Agent Carter" on Nov. 4 during its Marvel 75th anniversary special. The scene co-starred Dominic Cooper, as a younger Howard Stark and his butler, the original Jarvis, played by James D'Arcy.

The network will also premiere the new musical comedy "Galavant" on Sunday, Jan. 4. The show will replace "Once Upon a Time" at 8 p.m., but "Once" will return on March 1.

"Galavant" stars Joshua Sasse, Timonthy Omundson, Vinnie Jones, Mallory Jansen, Karen David and Luke Youngblood. The show has big named guest-stars planned including Ricky Gervais, John Stamos, Hugh Bonneville and "Weird Al" Yankovic.

ABC also announced that the "TGIT" lineup, which includes "Grey's Anatomy," "Scandal" and "How to Get Away With Murder," will have its midseason premiere on Thursday, Jan. 29.