Which alter ego did Beyoncé use for her more aggressive stage persona?

Beyoncé used the alter ego Sasha Fierce for her more aggressive stage persona.

She described Sasha Fierce as a performance character that helped her separate her private self from the confident, highly energetic figure onstage. The name became especially prominent during the creation and promotion of her 2008 album I Am... Sasha Fierce.

That double album was designed around two contrasting sides. The “I Am...” disc emphasized more personal and emotionally direct songs, while the “Sasha Fierce” disc focused on uptempo tracks and stage-oriented performances. Songs associated with the project included “If I Were a Boy,” “Single Ladies (Put a Ring on It),” and “Diva.”

Beyoncé later said she no longer needed the alter ego because she had grown comfortable combining those aspects of herself. Sasha Fierce was therefore not a separate recording artist or legal identity; it was a creative persona used in her music and performances.