The 29-year-old Hobbit actor seemed in good spirits as he chatted to pals over a few drinks.
"He seemed to be having great craic," an onlooker said. "He was in with a load of his acting buddies."
Clondalkin native Aidan is being tipped as the next big thing. Not only is he starring in Peter Jackson's blockbuster Hobbit trilogy, but he's just finished filming Mortal Instruments: City of Bones; a sci-fi series based on Cassandra Clare's best selling books.
Aidan, who previously acted in RTE's The Clinic, will star alongside Love/ Hate's Robert Sheehan and The Tudors star Jonathan Rhys Meyers in the upcoming vampire flick.
Despite starring in what will undoubtedly be some of next year's biggest movies, Aidan is staying calm.
"I don't think until the first Hobbit movie comes out that anything is really going to change for me," he said. "I'm just going to keep working. In that regard, nothing's changed".
The star wasn't the only thespian in Lillie's this weekend, Liam Cunningham and Leigh Arnold were also spotted in the celeb haunt.
And the crew of History Channels The Vikings let their hair down and celebrated the end of their 18 week shoot.