Well, think again. While we did get a very brief bit of voice acting from Hayden Christensen, we never actually saw Anakin's face — even though recent books confirmed his Force ghost was hanging out with Luke in the time before The Force Awakens.
It felt like a bit of a letdown (personally, I just really wanted to see ghost Vader), especially since Rise of Skywalker never explained this absence. However, a brilliant new fan theory could finally reveal why Anakin was missing in action right when the good guys needed him most.
The plot of Rise of Skywalker hinges on a pair of MacGuffins called Sith Wayfinders. These devices act as maps to Emperor Palpatine's secret location on the planet Exegol, and much of the movie focuses on Rey's quest to track a Wayfinder down.
What does anyone of this have to do with Anakin? A whole lot, it turns out.
As redditor u/Maximus_Decimus92 points out in a post titled "Wait a minute...(question regarding the Wayfinders)," if one of the Sith Wayfinders was hidden on the planet Mustafar by Darth Vader's castle, then Vader himself (aka, Anakin) almost definitely knew where it was. So then why didn't Anakins' Force ghost tell Luke where to find it sometime between Return of the Jedi and The Force Awakens?
Rise of Skywalker makes it clear that Luke was specifically looking for that Wayfinder because he knew it was the only way to ensure Palpatine never came back. The idea that Anakin was hovering around his son without offering the information Luke needed is just plain... embarrassing.
"Maybe that's why Anakin's ghost didn't appear at the end," u/Maximus_Decimus92 writes. "He was too embarrassed to show up because he forgot to tell his son where they Wayfinders were. Whoops, uh...awkward. I'm not gonna show up for the final shot. You got this, kids!"
This whole concept may feel more like the setup to a standup routine than a serious fan theory, but there's a kernel of truth to it. There's no arguing that Vader didn't know about the Wayfinders. In fact, we're pretty sure the one on Mustafar was genetically coded to his bloodline, which is why Kylo was able to recover it — the same goes for Rey grabbing her Grandpa Sheev's hidden Wayfinder on the wrecked Death Star.
So either Anakin forgot about the Wayfinder or he just never got around to telling his son about it. (Maybe there's a really cool cantina in Force ghost heaven.) Either way, that would certainly explain why he never showed up in The Rise of Skywalker. After all, you'd be pretty embarrassed too if you accidentally let the evilest guy in the galaxy come back from the dead.
The Rise of Skywalker is somehow still in theaters.