Eleanor Shellstrop - The Good Place
Eleanor's problematic behavior is what landed her in "the good place" in the first place, and as we have seen in flashbacks, she doesn't have a very good relationship with her parents, either. Is there even a family dinner for her to go to? If it's with her good place friends then she needs to learn something from Chidi's ethics classes first.
Black Siren - Arrow
Being from a different Earth doesn't disclude you from family events, right? She may not be their Laurel, but she still is Laurel Lance. Unfortunately, her killing sprees in Star City have landed her on the do-not-invite list, and it's going to take a lot before Quentin and Sara accept her as part of their family, even as a new Laurel.
Mon-El of Daxam - Supergirl
Mon-El's family life may be garbage, but he shouldn't be invited to Kara's family dinners, either. His misogynistic behavior hasn't changed since he was the Prince of Daxam, and it's not something that any family should be proud to have around them.
Amaya Jiwe - Legends of Tomorrow
Amaya's situation, like Black Siren's, is unique. Showing up at a family dinner in 2017 would be beyond awkward considering she's supposed to be dead, and she was living in the 1940's. The mini reunion between Amaya and Kuasa had enough awkward tension, there doesn't need to be a big event with everyone else.
Lyor Boone - Designated Survivor
Lyor may be President Kirkman's trusted political advisor, but he's sure to be a terrible guest. His track record proves he'll say whatever he needs to, and that's not good no matter what political side you're on.
Billy Hargrove - Stranger Things
Please, don't invite Billy anywhere. His pattern of abusive behavior may be somewhat because of his life growing up, but that's not any excuse. Plus, the way he behaves toward Lucas and attempts to get his stepsister away from him looks to be a racist issue, which is only the cherry on top. Just, please, keep Billy out of your lives.