The answer is:
REHEARSAL
Reasoning:
Each of the nine entries in the puzzle is a fictional character, along with a list of dates. It seems reasonable to assume, since the title of the puzzle is Actors, that we should find the actor who played each character on the appropriate dates. So for example, Talos is a character played by Ben Mendelsohn. Using IMDB as a reference, we note that he played Talos in Captain Marvel in 2019, Spider-Man: Far from Home (2019, uncredited), and in Secret Invasion (2023, TV). But, the date 2019 is listed twice. Typo? I think not!
Continuing down the list we see that each list of dates is exactly one date too long! For example, in the second entry, Cate Blanchett played Galadriel in six Lord of the Rings movies, but not in 2007. Running this down, we end up with the following actors, and odd dates out:
Talos (MCU) - Ben Mendelsohn - 2019
Galadriel (LotR) - Cate Blanchett - 2007
Dr. Alan Grant (Jurassic Park) - Sam Neill - 1995
Mark Darcy (Bridget Jones's Diary) - Colin Firth - 2010
Hildegarde Schmidt (Murder on the Orient Express) - Olivia Colman - 2018
Camilla Fritton (St. Trinian's) - Rupert Everett - 1994
Marcus Corvinus (Underworld: Evolution) - Tony Curran - 2010 TV
Nicola Murray (The Thick of It) - Rebecca Front - 1995
M (James Bond) - Bernard Lee - 1937
Next step:
We were fortunate in having Colin Firth and Olivia Colman together, since both had major roles as British royalty: Colin Firth as King George VI in The King's Speech, and Olivia Colman as Queen Elizabeth II in The Crown (though this is not the role that is actually referenced). Looking at the other odd dates out, each of these actors appeared as a member of British royalty in a film/TV show during the odd date out!
Ben Mendelsohn - King Henry IV - The King
Cate Blanchett - Queen Elizabeth I - Elizabeth: The Golden Age
Sam Neill - King Charles II - Restoration
Colin Firth - King George VI - The King's Speech
Olivia Colman - Queen Anne I - The Favourite
Rupert Everett - King George IV - The Madness of King George
Tony Curran - King Stephen I - The Pillars of the Earth
Rebecca Front - Queen Mary II - England, My England
Bernard Lee - King William III - The Black Tulip
Finally:
We have a list of names and numbers, so let's extract! The fourth letter of Henry is R (Henry IV). Going down the list gives:
R - henRy IV
E - Elizabeth I
H - cHarles II
E - georgE VI
A - Anne I
R - geoRge IV
S - Stephen I
A - mAry II
L - wiLliam III