Late in the film, Darth Vader does not recognize C-3PO who is in Cloud City with Han Solo, Chewbacca, and Leia. Although C-3PO is not completely assembled in the scene, he is definitely visible to Vader.
When Anakin befriended a group of stranded travelers, C-3PO was introduced to R2-D2, their heroic astromech. The two quickly became a duo, though when Anakin departed Tatooine to become a Jedi, he left his droid behind. C-3PO continued to serve Shmi, as well as her new husband, Cliegg Lars, and their son Owen.
As a consequence of this process, C-3PO had to undergo a complete memory wipe, and he agreed to it. However, R2-D2 had a backup of his friend's memory, and by the end of the movie, C-3PO's memory had been restored.
Plot summary. Following the Declaration of a New Order and the end of the Clone Wars, the droid duos C-3PO and R2-D2 were taken in by Senator Bail Prestor Organa aboard the Sundered Heart, who orders the protocol droid's memory wiped. 3PO was in doubt, and tried to explain to Captain Raymus Antilles.
Yes, he did. In the comic Thank the Maker, Darth Vader comes into possession briefly of 3PO's disassembled head while on Cloud City.
Perhaps, the old creature simply forgot. Late in the film, Darth Vader does not recognize C-3PO who is in Cloud City with Han Solo, Chewbacca, and Leia. Although C-3PO is not completely assembled in the scene, he is definitely visible to Vader.
R2-D2 has probably seen more action than all of the sequel characters put together, and has met a long list of Jedi from across time, including master Yoda. R2-D2 has even carried out special missions for the Jedi Council.
Obi-Wan Kenobi has no idea who C-3PO is when they meet in “Star Wars: A New Hope” even though the prequel trilogy later told us that the two certainly knew each other.
During the Clone Wars, it was common practice to wipe the minds of astromech droids after every mission to avoid the risk of Separatists taking valued information. But Anakin remained staunchly against this idea for R2-D2, meaning the droid never had to worry about losing the memories of his past.
C-3P0 didn't; his memory was wiped at the end of Revenge of the Sith to prevent him from spilling the beans. C3PO, no. His memory was wiped at the end of Revenge of the Sith. A blabbermouth like him can't be trusted with sensitive information.
After a chase through an asteroid field, the Falcon escapes to Cloud City at Bespin. While exploring a room in Cloud City, C-3PO is blasted by an off-camera stormtrooper.
By claiming he's never owned a droid, he applies the same tactic as he did with his embellishment about Anakin. He hasn't owned a droid because R2-D2 is his friend. No one can "own" him, and to claim to have done so disrespects the countless ways the little astromech has saved the galaxy.
R2-D2 was in on the scheme to keep the secret away from Luke and Leia. He was devoted to the Skywalker family, and at the guidance of Obi-wan and Yoda, he would have maintained that secret in order to help protect the twins.
Future of Star Wars
Vader did recognize C-3PO, and R2 quite possibly recognized Yoda, but either couldn't or chose not to inform Luke about him.
"Downfall of a Droid" Episode Guide | The Clone Wars – Season 1, Episode 6. "Trust in your friends, and they'll have reason to trust in you." R2-D2 is lost during a fierce space battle -- and Anakin must find him before the Separatists discover the Jedi military secrets locked in his memory banks.
“It's good to fly with you again, my old friend,” the old man said, so softly Han wasn't sure he had heard him right. C-3P0 didn't; his memory was wiped at the end of Revenge of the Sith to prevent him from spilling the beans.
After the battle, R2-D2 and C-3PO were the sole witnesses to the marriage of Anakin Skywalker and Padmé Amidala in Lake Country. After this Padmé gave ownership of R2 to Anakin while she kept 3PO.
Revenge of the Sith
After Anakin falls to the dark side of the Force and becomes Darth Vader, he takes R2-D2 with him when he goes to assassinate the Separatist council, but tells him to stay with the ship.
Presumably Palpatine planned to have Anakin join him at that point and so told the clones not to kill him when he gave out Order 66.
While, it may be true Chewbacca met Yoda and Ahsoka, there is no indication that he met Anakin. Even if Chewbacca has met Anakin, Chewbacca would have assume Anakin was one of those Jedi killed in Order 66.
Vader agreed to help the handmaiden, silently recalling the time he spent with Padmé in the process. In this moment, he was once again Anakin Skywalker, a young man in love who simply wanted to change the world for the better.
Does Darth Vader remember being Anakin? Yes. Yes, he remembers his name but feels it has no meaning to him anymore.
R2-D2, the indomitable droid and mainstay of the Star Wars series, may be responsible for one more incredible feat: saving Grogu.
This meant that he would be able to keep the amount of casualties to a minimum. Therefore, he stored the lightsaber inside R2 to force himself to only use it when it was necessary.
Palpatine has looked for Yoda and sent his Inquisitors in search of him, but has never found him. This isn't a concern to the Emperor, since he knows he has already defeated the old Jedi to the point where Yoda can't stop him, but he still wishes to kill him.