The best thing about Willem Dafoe returning for Spider-Man: No Way Home is his conditions. Most people think of pay, status symbols, or crazy demands when they think of an actor with conditions, but that's not the case here. Willem Dafoe requested something completely different, and he was doing it for the fans.
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Spider-Man: No Way Home Willem Dafoe Demands
Willem Dafoe was pitched the idea of his Green Goblin returning in Spider-Man: No Way Home before there was a script. While he was immediately receptive to the idea, he was adamant that they would not just include him as a cameo. So he could give a better performance than in Spider-Man, he wanted to fully immerse himself in character again.
In contrast to Spider-Man 2 and 3, where he did a legitimate cameo, Willem Dafoe wanted to put on the suit, give the mannerisms, and play the character as he would. In his own words:
"I'll come back if there's something really good. If it's just a cameo or a little tip of the hat, I'm not sure. If it's something substantial, Yeah… I want to do the action because that's fun for me and also it's really impossible to add any integrity or any fun to the character if you don't participate in these things. Because all that action stuff informs your relationship to the characters."
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William Dafoe is a famous actor, so he doesn't really need to argue over a big check—he just wants every performance to be memorable. Based on the reviews for No Way Home, he succeeded.