Season 4 (Supergirl)

​​​ was renewed for a fourth season by The CW on April 2, 2018. It premiered on October 14, 2018.

Main cast

 * Melissa Benoist as Kara Danvers/Supergirl and Supergirl's copy
 * Mehcad Brooks as James Olsen/Guardian and Jimmy
 * Chyler Leigh as Dr./Director Alex Danvers and Alex Danvers
 * Katie McGrath as Lena Luthor
 * Jesse Rath as Querl Dox/Brainiac 5
 * Sam Witwer as Professor Ben Lockwood/Agent Liberty
 * Nicole Maines as Nia Nal/Dreamer
 * April Parker Jones as Colonel Lauren Haley
 * David Harewood as J'onn J'onzz

Recurring cast

 * Brenda Strong as Dr. Lillian Luthor
 * Andrea Brooks as Eve Teschmacher
 * David Ajala as Manchester Black
 * Tiya Sircar as Fiona Byrne
 * Rhona Mitra as Mercy Graves
 * Robert Baker as Otis Graves
 * Lynda Carter as Olivia Marsdin
 * Bruce Boxleitner as President Baker
 * Anthony Konechny as Raymond Jensen/Parasite
 * Jon Cryer as Lex Luthor
 * Azie Tesfai as Kelly Olsen
 * Hannah James as Maeve Nal
 * Jessica Meraz as Pamela Ferrer/Menagerie
 * Louis Ozawa Changchien as The Hat

Confirmed plot points

 * The theme of the season is, "What Is Stronger; Hope or Fear?"
 * The Red Son-ish cliffhanger from the Season 3 finale will become a big centrepiece in the latter part of the season.
 * Ben Lockwood/Agent Liberty and Lex Luthor are the main antagonists of the season.
 * David Harewood will direct an episode this season.
 * James will exact his revenge on Lex Luthor for being shot.
 * Carl Lumbly will return in episode 17 as M'yrnn J'onzz.
 * Eve Teschmacher's backstory will be explored.
 * Kelly Olsen and Alex Danvers will get close.

Confirmed new characters

 * Coldcast: TBA.

Trivia

 * This season airs on Sundays at 8/7c, as opposed to the past three seasons, where it aired on Mondays at the same time.
 * Manchester Black was originally going to be the main antagonist of this season.
 * Jeremy Jordan was supposed to appear in a recurring role this season, but unfortunately he was unable to. He will possibly appear in the fifth season.
 * This also means that this is the first season without Jeremy Jordan being featured in any shape or capacity.
 * This is the first season of Supergirl to have humans as main antagonists.