Without question, the most well-known iteration of Supergirl to date is the version played by Melissa Benoist in the CBS/CW TV series, which ran for six seasons between 2015 and 2021. She's also the strongest of them all.
Supergirl told us Kara's story right from the beginning, detailing how she went from a young woman nervously hiding her secret to a powerful warrior who embraced her identity and became one of the Arrowverse's greatest heroes. She spent much of the first season doubting herself and her abilities, but by the end of season 2, she was capable of defeating even Superman.
Kara has been tried and tested over the course of the show's run, but she has never relented. Since her arrival on the scene as National City's protector, she has defeated members of her own Kryptonian family, Daxamites and their queen, a Kryptonian Worldkiller, Lex Luthor, an ancient race of alien warriors, and an unpredictable imp harnessing magic. She officially ascended to the role of Earth's Champion after defeating her cousin and played a pivotal role in saving the multiverse from complete annihilation at the hands of the Anti-Monitor. Oh yeah, and much like we've seen the Man of Steel do over the years, she was able to slow down time itself by flying around it at an incredible speed.
This version of Supergirl has done in all in six seasons and somehow still left us wanting more. She certainly has enough fight left in her to give us more, too, because the Arrowverse's Girl of Steel is by far the most powerful version of the character we have ever met. She has everything we know Supergirl to have, and so much more.