Fans gushed over the photos, one showing Barry kissing Brando’s head as he wore a Batman cape
The Batman star took a backseat to baby Brando who wore the titular superhero’s costume and was snapped in his mum and dad’s arms.
Keoghan dressed up as the hero’s sidekick Robin while his Cavan girlfriend Alyson who took on the Riddler.
Sharing a photo of the family to Twitter, the Hollywood actor wrote: “ROBIN needs his BATMAN.”
Fans gushed over the photos, one showing Barry kissing Brando’s head as he wore a Batman cape.
"Oh my god the cutest family ever,” one said.
“THIS IS SO CUTE,” another wrote in all caps while others shared heart emojis for the “baby Batman.”
The Love/Hate actor welcomed his first child Brando with his girlfriend Alyson in August.
Barry announced the couple had finally become parents with a sweet Instagram tribute.
He shared a black and white photo of him and his partner cuddling their newborn, which he captioned: “Welcome to the pack my boy, B R A N D O.”
It has been a big year for the Irish star, who has seen big roles in Marvel’s Eternals and as the iconic villain the Joker alongside Robert Pattinson's The Batman.
His role was an early tease of the super villain, simply credited at the end of the movie as “Unseen Arkham Prisoner.”
Most of Keoghan’s scenes were cut from the film, though one deleted clip was later released – hinting that we may see more of the Dubliner in the DC franchise yet.
The star has shared he is more than willing to reprise the part and join stars like Joaquin Phoenix and Heath Ledger in the role.
"I'd love to show a little arc of him,” he told GQ.
"If I could bring him to life that would be amazing and give you my version, which you've not seen."