Supergirl will be showing us a little Mercy next season: Rhona Mitra (The Last Ship) is joining the Season 4 cast of The CW’s superhero drama in a season-long recurring role as villainess Mercy Graves, our sister site Deadline is reporting.

Mercy Graves is known from the comics as super villain Lex Luthor’s longtime bodyguard. “But with both Lex and Lillian in prison,” according to the official description, “Mercy is stepping out of the Luthor shadow and running her own show. With her biting wit and lethal brawn, Mercy steadily becomes a key figure in National City’s growing ‘human-first’ movement.”

Plus, Robert Baker (Grey’s Anatomy, The Originals) is joining the cast in a recurring role as Mercy’s brother Otis. He serves as Mercy’s right-hand man: “What he lacks in brains, he makes up for with his savant-like abilities to assassinate aliens.” Season 4 of Supergirl kicks off Sunday, Oct. 14 at 8/7c on The CW.

Mitra’s recent roles include TNT’s The Last Ship, FX’s The Strain and Cinemax’s Strike Back. She also appeared in multiple episodes of Nip/Tuck, Boston Legal, The Practice and Party of Five.