- Black Widow (Natasha Romanoff) (Main story and flashback)
- Black Widow (Yelena Belova) (First appearance)
- Melina Vostokoff (First appearance) (Main story and flashback)
- Red Guardian (Alexei Shostakov) (First appearance)
- Rick Mason (First appearance)
- Secretary Thaddeus Ross
- Red Room Program
- Avengers (Mentioned)
- King T'Challa (Mentioned)
- Natasha's mother (Mentioned)
- Hydra (Mentioned)
- Winter Soldier Program (Mentioned)
- Alexei (pig) (First appearance)
- North Institute (Mentioned)
- Fanny (dog) (First appearance)
- Valentina Allegra de Fontaine (First appearance historically)
Races and Species:
- Sokovia Accords (Mentioned)
- Black Widow's Suit
- Black Widow's Batons
- Black Widow's Gauntlets
- Panther Habit (On-screen)
- Hawkeye's Suit (On-screen)
- Hawkeye's Bow (On-screen)
- Taskmaster's Shield
- Taskmaster's Bow and Arrow
- The Antidote
- Photostatic Veil
Following the events of Captain America: Civil War, Natasha Romanoff finds herself alone and forced to confront a dangerous conspiracy with ties to her past. Pursued by a force that will stop at nothing to bring her down, Romanoff must deal with her history as a spy and the broken relationships left in her wake long before she became an Avenger.
- Scarlett Johansson as Black Widow / Natasha Romanoff
- Ever Anderson portrays a younger Natasha
- Florence Pugh as Yelena Belova
- Violet McGraw as Young Yelena Belova
- David Harbour as Red Guardian / Alexei Shostakov
- O-T Fagbenle as Rick Mason
- Rachel Weisz as Melina Vostokoff
- William Hurt as Thaddeus Ross
- Olga Kurylenko as Taskmaster
- Ray Winstone as General Dreykov
- Olivier Richters as Ursa / Mikhail Ursus
Additionally, Julia Louis-Dreyfus makes an uncredited appearance as Valentina Allegra de Fontaine in the film's post-credits scene, a role originally intended to debut in this film, before in the Disney+ series The Falcon and the Winter Soldier.
- This film has had multiple changes to its US release date due to the COVID-19 pandemic:
- Originally slated to be released on May 1, 2020 in the US, the release was pulled on March 17, 2020. On April 3, 2020, it was announced that the release date for this film had been pushed to November 6, 2020.
- In September 2020, the film was pushed back again to May 7, 2021.
- In March 2021, the film was pushed back for a third time to July 9, 2021, releasing in theaters and on Disney+ with Premier Access on the same day.
- This was originally intended to be the Marvel Studios property that launched Phase 4 of their cinematic universe. However, due to the film's release date delays, the Disney+ series WandaVision began Phase 4 instead, with Black Widow instead being slated as the first film of Phase 4.