Conor McGregor can be quite the polarizing figure, but he's good in Donald Trump's eyes ... 'cause POTUS just called Notorious one of his favorite Irishmen!!

No. 47 gushed over the UFC superstar with Ireland's Prime Minister Micheal Martin at the White House on Wednesday ... and while they talked some politics, Trump was also asked to name his favorite famous figure to come from the Emerald Isle.

"I do happen to like your fighter," he said. "He's got the best tattoos I've ever seen."

"Conor's great, right?"

He then complimented the folks of Ireland as a whole, calling them "tough people."

"They're smart people and they are passionate people."

Trump name-dropping Conor shouldn't be too surprising -- he helped Dana White and UFC in its early days ... and he's shown up to plenty of fight nights in person.

McGregor has praised Trump himself in the past, posting his support back in July after the assassination attempt.

"A 78-year-old multiple billionaire he should be on a yacht on the med touring golf courses," McGregor said at the time. "But he is not. He is in Pennsylvania spitting out bullets! Running for the love of his country! God speed Donald! God bless the United States."

His feelings shifted a bit in August ... after Trump called his rival, Khabib Numagomedov, his favorite UFC fighter.

"Campaign ending decision," he said at the time.

It seemingly wasn't all too serious, though, as McGregor attended Trump's inauguration in January ... so he clearly got over it if it really did irk him.

No response yet from Notorious, but we imagine it won't be long until he shares his thoughts on the praise.