As far as I know, the five actors to have played the role of Batman in films are Adam West, Michael Keaton, Val Kilmer, George Clooney, and Christian Bale. Is it grammatical to call them "the batmen"?
I would say that strictly speaking it is not. Irregular plurals carry if they are instances of the base word. A "fireman" is a type of man, so "firemen" is the appropriate plural, but the "Toronto Maple Leafs" are not leaves.
Since Batman is a proper noun, Batman does not designate a type of man but the name for one particular man, so the irregular plural does not carry. It should be "the Batmans". However, this is, at least to my ear, somewhat awkward.
So you have three choices. If you want to be strictly correct and not be awkward, "the actors who portrayed Batman". If you don't mind being a bit awkward, "the Batmans". If you can tolerate a few points off on your poetic license, and can see Batman as not so much a proper noun but as a type of man, then why not ... "the Batmen".
You could write the batmen, and if you’re writing an attention-getting headline, maybe you should. But it is definitely unusual enough to call attention to itself, and you typically don’t want to distract the reader from what you’re trying to say.
Batmans sounds obviously wrong to me, unless you’re going for laughs. Cf. librarymans.
Maybe it’s just me but it seems like real sentences using batmen tend to be a bit informal in tone:
The result was 3 pages of Batmen in their off-hours, when they’re just kicking back and taking a break from being the Batmen we all know and love.
while those using batmans are extremely informal in tone:
I freely admit I love ALL THE BATMANS.
i think the batmans weapons cannot even harm iron man as he withstands powerful missiles.so ironman wins the game.
All “decent” actors when giving the approriate character… but not in this type of movie…. maybe in the batmans of the 90’s…
Yes, it is grammatical.
Batman, UK noun, plural Batmen. The personal servant of an officer especially in the British Armed Forces
No. Batman is a single character. Multiple actors have played the character, but there's only one Batman.
Batman is the name of a character. Philip Seymor Hoffman played Truman Capote in the movie Capote. In referring to this character, if there were remake, the various portrayals would not be Trumen.
It is conceivable that the various players collectively could be referred to as the Trumans, but that feels very artificial. Each of the actors would have played Truman and collectively they played Truman or the Truman roles.
While it is arguable that there have been many Othellos, I think it is much better form to indicate that many have been Othello, that is, when referring to character names, the plural should be avoided. (Perhaps the only exception is a mulitplicity of Elvises and only when they appear in multiples at the same time, such as in Honeymoon in Vegas.)
Strictly speaking, there have not been multiple "Batmen," but rather "multiple portrayals of Batman." Not only is it not grammatical to say "the batmen," it is factually incorrect to refer to the actors as such. Certainly, it's an appealing construction - after all, it sort of rolls off the tongue. However, that's not the nature of acting.
Actually, the number of actors who have portrayed Batman is seven not five. Lewis G Wilson; Robert Lowrey; Adam West; Michael Keaton; Val Kilmer; George Clooney and Christian Bale.
Note the author of the article (and also the OP) wrote Batman and nothing similar to "There have been seven Batmen in the TV series and movie history." The noun batmen is of course grammatical, but why shouldn't it be? The plural of man is men, and as @Jrfras mentioned in their post, batmen are the personal servants assigned to a commissioned officer in the British Armed Forces. Therefore the following sentences would be perfectly correct
Yesterday police arrested a batman.
Yesterday police arrested several batmen.
However, the nouns Batman and Caped Crusader are both proper nouns and it is the norm in English to capitalize proper nouns. Some proper nouns can be pluralized when we mention them as a unique group for example; the Simpsons, the Bushes, the Marches, the Himalayas; the United States; the Yankees; the Green Bay Packers etc.
But the role of Batman is one, the superhero in every film, comic strip, TV series is one, there has never been seven "Batmen" simultaneously. The seven actors are never referred to as "the Batmen" or, ex-Batmen. If two or more were called Batmen the term would be ambiguous, the speaker/writer might be stating that the actors were once private soldiers who were servants to high ranking officers.
Wikipedia mentions in its article Batman (military)
J. R. R. Tolkien took the relationship of his characters Samwise Gamgee and Frodo Baggins from his observations while in military service during World War I of the relationship between a batman and his officer
Popular ITV drama Downton Abbey featured a valet named Bates who served Lord Grantham as a batman in the Boer War.
In the BBC sitcom Blackadder Goes Forth, set during World War I, actor Tony Robinson portrays Private S. Baldrick, the bumbling and incompetent batman to Captain Edmund Blackadder.
Google Books Ngrams seem to suggest that the plural forms "are/were batmen" and "are/were Batmen" are non-existent in American English whereas the expressions "was/is batman" enjoyed its peak of usage between 1916 and 1920, and the proper noun "was/is Batman" has had the upper hand since the 1960s.
The only group of superheroes I can think of whose name terminates with men is...
Within the Marvel Universe, the X-Men are widely regarded to have been named after Professor Xavier himself. Xavier however claims that the name "X-Men" was never chosen to be a self-tribute. [...] The original explanation for the name, as provided by Xavier, is that mutants "possess an extra power... one which ordinary humans do not!! That is why I call my students... X-Men, for EX-tra power!".
On August 2, 2014, the New York Times published an article titled "Spider-Man Unmasked! Elmo and Minnie, Too" about people who dress up as cartoon characters in order to pose for pictures and receive tips from tourists in Times Square—and this very question came up, not in the context of multiple instances of Batman but of multiple instances of Spider-Man. Here is how the New York Times handled the issue:
The performers have come under even greater pressure since a recent violent confrontation between a man dressed as Spider-Man and a police officer. The man was arrested after fighting with the officer, who had responded to the man’s aggressive solicitation, the authorities said.
The episode was the latest in a recent series of unpleasant encounters that have cast a cloud over the street performers. Two other Spider-Men were arrested in separate episodes in June, one charged with groping a woman and the other charged with assaulting a woman (he was found not guilty but was fined for harassment).
A caption in the same story mentions "the Times Square hurly-burly of Elmos, Minnie Mouses and Batmen who pose for photographs and then coax customers for tips." On the other hand, the same story also cites "an enclave of Mickey Mouses and Sheriff Woodys" (Sheriff Woody being the name of a character from the Toy Story movies)—but if you take Spider-Man/Spider-Men and Batman/ Batmen, instead of Spider-Man/Spider-Mans and Batman/Batmans, I would have expected the Sheriff Woody pairing to be Sheriff Woody/Sheriff Woodies, not Sheriff Woody/Sheriff Woodys.
Its hard to avoid the conclusion that the New York Times's treatment of Spider-Men (on the one hand) and its treatment of Sheriff Woodys (on the other) represent inconsistent ways of handling the same problem of rendering a singular proper (but fictional) name as a plural.
A name, proper noun, or a character. But Batmen sounds right .
Two examples from a UK based newspaper :
The gathering of 542 Batmen (and women) kicked off a campaign for a United Way charity.
In this short film released to commemorate Batman’s 75th birthday, old man Bruce Wayne and Terry McGinnis fight against the Dark Knight’s past incarnations – Batmen from comics, cartoons and live action. Happy Birthday, Bats!
What about Bats......
Batmen is grammatically correct, and the contextual meaning will probably be understood by the reader.
Whether or not you would use the word is more about style and preference. You could avoid the word by writing "the actors who've played Batman" or you could be lighthearted and use "Bat-Thespians" for example to go with naming convention of Batman's tools.