Enlarge Image ABC/Richard Cartwright

Peggy Carter knew her worth. Fans knew her worth. But sadly, ABC didn't. The network canceled "Marvel's Agent Carter" on Thursday after just two seasons.

The compelling post-WWII plot lines and stellar cast, including Hayley Atwell in the lead role, earned respect from both TV critics and Marvel fans.

But ABC decided to pull the plug after low ratings, according to The Hollywood Reporter.

Of course -- major spoiler! -- Peggy Carter's fate was already sealed in the new movie "Captain America: Civil War." She also got a quick shout-out in a recent "Agents of S.H.I.E.L.D" episode.

Unless Marvel decides to give Carter her own feature film continuing her adventures from the TV show, it doesn't look like we'll be seeing her again. That hasn't stopped fans from starting a petition to urge Netflix to save the show. More than 5,900 people have signed the petition so far.

"Agent Carter is one of the only solely female-based shows on the air of the superhero variety," fan Emma Tonn, of Dubuque, Iowa, said in the petition's comments section. "Peggy Carter is such an amazing character, and with lines such as 'I know my own worth,' she's also an exemplary role model."

ABC has said goodbye to "Agent Carter," but Atwell will be returning to the network. The actor has already signed on for the new legal drama "Conviction."

Sadly, "Agent Carter" wasn't the only Marvel casualty. ABC also decided not to pick up "Agents of S.H.I.E.L.D." spinoff "Marvel's Most Wanted." That series was set to center on disavowed agents Bobbi Morse (aka Mockingbird, played by Adrianne Palicki) and Lance Hunter (played by Nick Blood).