Without any doubt in my mind, Dustin Hoffman. I even have a sort of headcanon with the “Tony Stark is Darcy’s dad” Trope : Darcy doesn’t know Stark is her dad until the same year her grandad gives her the letter her mother (his daughter) wrote for her and instructed him to never read. She was supposed to have it at her 18th birthday but grandad never cleans anything (she knows because he’s the one who raised her after her mom death when she was three). So she learns who is her real father a little too late because she read the shieldra info dump on the internet and discovered her file – just like Stark did. They talked and grandad had to make amends by going into Stark Tower, meeting her with Tony while all the avengers & co were listening with avid curiosity. Pepper invited him because of his building being fumigated and he never left. Then Darcy starts dating an avenger and grandad likes to be a little shit so he lies by creating a list of things he wants for the perfect suitor of his little Dee and knows anything he asks he will get – Dustin Hoffman as the avengers grandad creating havoc for his amusement and just plotting for a good laugh basically because I always loved him?