Winick, best known for big screen romantic comedies, died after a lengthy battle with brain cancer.
And Seyfried, who worked with him on his last film, Letters To Juliet, remembers her time with him fondly, telling The Hollywood Reporter, "Gary's heart was so big I think each of us who loved him have a piece of it now. It's unreal that he's gone and I'll miss my friend more than I can say."
Garner was the star of Winick's film 13 Going on 30, and has praised the moviemaker's friendly nature, adding to Entertainment Weekly: "Gary and I had the most successful collaboration possible. I don't mean success in terms of box office, or from anyone else's point of view other than my own. I left it better at what I do. He was one of the most inclusive people you could ever meet, and I was energised by our creative mess together everyday. From then on, there wasn't a single project that I didn't try to do with him.
"I think everybody who was a friend of Gary's considered him one of their best friends. He had a hundred best friends. He just was unafraid of being intimate. And that spilled over into his directing."