Though she played a major role in the two-part season finale, it seems Calista Flockhart’s Cat Grant won’t actually be sticking around in Season 3 of Supergirl. At least, not permanently.
TV Line reports that, though Flockhart was initially listed alongside the rest of the Season 3 cast, she's still just a guest star in Season 3. Much as in Season 2, the plan is for her to show up in a few guest appearances next season. It seems Flockhart still isn’t keen to relocate to Canada for the gig, so she won’t be a major presence next season. Which sucks, because Cat Grant is awesome, and her return in these last two episodes was a major creative spark.
Though Flockhart won’t be around for most of the season, Supergirl is looking to cast a new player in Season 3. As expected, the main villain in Season 3 will be the DC baddie Reign (that other, mystery baby sent off from Krypton). The studio is casting for the role now, and the character is expected to appear in 12 or more episodes.
(Via TV Line)