Shia LaBeouf was on daddy duty Christmas Eve ... spending some quality time with his daughter Isabel at Universal Studios Hollywood. With the one-year-old strapped to his back in a baby carrier ... the actor stirred up more excitement running around following a meet and greet with The Grinch. Fatherhood clearly suits Shia, who was filmed by onlookers grinning ear to ear ... and stopping to chat with people who recognized him. Shia welcomed Isabel with actress Mia Goth last year ... revealing months later on Jon Bernthal's podcast, "Real Ones," his daughter makes him want to transform into a stand-up guy. This comes after his ex-girlfriend FKA Twigs filed a lawsuit against LaBeouf in 2020 for assault and sexual battery. The trial date is set for October 2024. (TMZ)