When her son Samuel asked for a superhero party to celebrate his fourth birthday on Feb. 27, Garner said Affleck went all out with his costume.
Affleck, 43, didn't have to search hard for his costume as he's set to play the Caped Crusader in the upcoming film, "Batman v Superman: Dawn of Justice," out March 25.
Garner's compliment came after her very candid interview in Vanity Fair.
The "Miracles from Heaven" actress said in the magazine that despite their split in June 2015 after 10 years of marriage, their relationship was authentic.
"I didn't marry the big fat movie star; I married him," Garner said. "And I would go back and remake that decision. I ran down the beach to him, and I would again. You can’t have these three babies and so much of what we had. He’s the love of my life."
She continued: "He's the most brilliant person in any room, the most charismatic, the most generous. He's just a complicated guy. I always say, 'When his sun shines on you, you feel it.' But when the sun is shining elsewhere, it's cold. He can cast quite a shadow."