Barbara Morse was an S.H.I.E.L.D. agent whose assignments made her an ally of the jungle lord Ka-Zar. She subsequently used the costumed identity of the Huntress and later Mockingbird to expose the corrupt activities of certain S.H.I.E.L.D agents. After being injured in her work she received a commendation by then S.H.I.E.L.D. Director Nick Fury, who used her information to expose dozens of subversives within S.H.I.E.L.D. Resigning from S.H.I.E.L.D., Mockingbird was hired to investigate Cross Technological Enterprises (CTE), where she clashed with security director Hawkeye. The two soon discovered that CTE was working for the criminal Crossfire helping to implement his plans to brainwash super heroes into killing each other off. The two joined forces against Crossfire and his underlings, becoming attracted to each other in the process. At the case’s successful conclusion, Mockingbird proposed to Hawkeye and the two married. When Hawkeye was appointed head of the West Coast branch of the Avengers, Mockingbird became the team's first new recruit and was instrumental in helping Hawkeye form the new team. Months later, during a time traveling adventure in 1876, Mockingbird was abducted and drugged by the crazed vigilante called the Phantom Rider (Lincoln Slade), who attempted to force her to become his bride. Regaining her senses, Mockingbird fought the Rider and allowed him to fall to his death. After the West Coast Avengers returned to their home era, Mockingbird kept the nature of the Phantom Rider’s death a secret. However, the Rider’s ghost soon appeared and told the Avengers what had transpired. Distraught that an Avenger (especially his wife) had allowed a man to die, Hawkeye became estranged from his wife, and Mockingbird re-entered into government service. She participated in Operation: Vigilance, a program to provide protection from any potential threat from the Vision, only to rebel once she discovered the program's full agenda. Helping the Avengers to rescue the Vision, she was gradually reconciled with Hawkeye. Together they helped train the Great Lakes Avengers and Mockingbird became good friends with Ashley Crawford. The pair eventually renewed their relationship, only for Mockingbird to perish while protecting Hawkeye from the demonic Mephisto. She has since been resurrected by the Grim Reaper for his Legion of the Unliving, but turned against him. Before returning to the realm in which she was paying her penance for killing the Phantom Rider, she gave a warning to the Avengers which eventually led to the resurrection of Hellcat.