The celebrated actor is no stranger to science fiction or fantasy, having starred in last year's reboot of the cult classic Dune, as well as X-Men: Apocalypse and several Star Wars films perviously.
However, his latest outing has seen him come in for some flak - and it's not even been released yet.
For those of you who are unfamiliar with said character, the official synopsis for Moon Knight, which is set in London, reads: "The series follows Steven Grant, a mild-mannered gift-shop employee, who becomes plagued with blackouts and memories of another life.
"Steven discovers he has dissociative identity disorder and shares a body with mercenary Marc Spector.
"As Steven/Marc’s enemies converge upon them, they must navigate their complex identities while thrust into a deadly mystery among the powerful gods of Egypt."
All sounds interesting enough, sure.
But just like Al Pacino, Kevin Costner and Keanu Reeves before him, it doesn't appear as though the 42-year-old has been able to perfect the British accent.
Since the trailer landed, lots of fans have compared Isaac's attempt to a bizarre imitation of Dick van Dyke.
One viewer wrote: "Excited for #MoonKnight but Oscar Isaac's accent has caught me off guard, it just sounds so weird on him."
Echoing the surprise, another chimed in: "So I watched that trailer because I was bored, can we talk about Oscar Isaac's English accent! Dude watched too many Guy Ritchie movies."
Oscar Isaac's Dick Van Dyke-esque British accent is singlehandedly going to make this immensely watchable, isn't it? https://t.co/SQNKOdMgX3— jacob! (@LongMacVampyr) January 18, 2022
Hilarious that Oscar Isaac’s terrible accent is the only thing making me curious about MOON KNIGHT— Chris (@ChrisRogers1138) January 18, 2022
just discovered from a tweet that apparently the accent oscar isaac is doing for moon knight is ENGLISH???— petite emmanon (@evemmore) January 18, 2022
"Oscar Isaac’s accent in the #MoonKnight trailer is literally like ‘ello guvna wot are ya dewin?!" put a third.
While another added: "Oscar Isaac's Dick Van Dyke-esque British accent is singlehandedly going to make this immensely watchable, isn't it?"
While the accent caught most people off guard, some fans of the character said they were confused as to why he was British in the first place when he was American in the comics.
Well, others pointed out that Marc Spector has dissociative identity disorder in the comics and has a number of alter egos, including Steven Grant - the lead in the new TV series - Jake Lockley and Mr Knight, so it's possible that Isaac will slip between accents in the series to fit with each persona.
And some actually came out to support Isaac for his attempt, saying people were simply overreacting.
"Oscar Isaac's British accent is pretty alright huh," said one.
While another added: "Will not be entertaining British criticism of Oscar Isaac’s cockney accent as Moon Knight until Benedict Cumberbatch’s 'American' accent as Dr. Strange has been raked over the coals enough times."
Moon Knight also stars Ethan Hawke and is set to land on Disney+ on 30 March.
Featured Image Credit: Marvel