7. Ruby Rose (Kate Kane) - Batwoman
Batwoman's first season received broadly positive reviews, though fans were left gobsmacked when star Ruby Rose, who played Kate Kane aka Batwoman, announced mere days after the season one finale that she wouldn't be returning for season two.
Rose later explained that an on-set back injury and the generally "taxing" nature of the shoot left her feeling burned out, after which the producers decided to write Kate out rather than recast the character.
And so, season two had the enormous challenge of introducing a new Batwoman, Ryan Wilder (Javicia Leslie), while explaining what the hell happened to Kate.
Thankfully fan reception to Wilder has mostly been positive considering the circumstances, and it was recently confirmed that a recast Kane will be appearing in the second half of season two, as played by Wallis Day.
Considering that such a sudden recast so early in a show's life could easily be the kiss of death, it's impressive how lithely Batwoman has rolled with the punches. For her part, Rose has been nothing but supportive of both Leslie and Day.