The mystery of Jack Pearson's (Milo Ventimiglia) death has dominated the fan discussion surrounding This Is Us — sometimes to the frustration of the cast and creators — but among the emotional highs and lows of the show, it's nice for fans to tap into the fun and intrigue of speculation every now and then.

That speculation has spawned some seriously great theories and some seriously nutty ones, so we asked stars Justin Hartley and Milo Ventimiglia which fan theories have been the weirdest to hear so far.

"One of them is that he's alive and he didn't die, but he just wanted everyone to think he was dead," Hartley told TV Guide. "So he faked his death, and Rebecca was in on it, and that's why the kids are mad at her now, and that's going to be like Season 4."

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Ventimiglia hadn't heard something as bizarre as a conspiracy (or Hartley's other two, aliens and dream sequences), but he does have a favorite.

"I always love when people point the finger at Miguel," Ventimiglia says. "But then again, I'm like no, that's his best friend. That's his closet confidant aside from his wife."

One thing we found interesting is that Hartley said he has yet to hear a fan theory that gets it right. There's a chance he just hasn't heard a lot of them, but on the other hand, the truth could be so far out there that fans just won't ever see it coming.

This Is Us returns Tuesday, Sept. 26 at 9/8c on NBC.

Milo Ventimiglia, <em>This Is Us</em>Milo Ventimiglia, This Is Us