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 Director Alex Danvers and Alex Danvers
 * Katie McGrath as Lena Luthor
 * Jesse Rath as Querl Dox/Brainiac 5
 * Sam Witwer as 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 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 centerpiece in the latter part of the season.
 * Ben Lockwood/Agent Liberty will be the main antagonist of this season.
 * This season, Brainiac 5 will socially butt heads with a couple people.
 * David Harewood will direct an episode this season.
 * Lex Luthor will be introduced this season.
 * James Olsen's sister will appear this season.
 * Manchester Black will form a group called "Elite", consisting of Menagerie, the Hat and Coldcast.

Confirmed new characters

 * Lex Luthor: He will shake things up in National City and go toe to toe with not only Supergirl, but his sister Lena Luthor.
 * Kelly Olsen: Kelly is an intelligent and insightful woman who spent time in the military in order to pay for medical school. She's recently discharged from the military and is currently finishing her training as a psychiatrist. She's got a large heart and cares deeply about others.
 * Quentin: A wide-eyed government attaché who is grateful when Supergirl saves his life. However, when he shows his true colors by attending an anti-alien rally, Supergirl aims to prove to Quentin that not all aliens are bad.
 * The Hat: A young Japanese man who gains the ability to be invulnerable and breathe fire after being merged with a demon, with his hat serving as his primary conduit.

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. Although, It's unknown if he will become the main antagonist in future episodes.
 * 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.