[Spoiler alert for Game of Thrones S06E05 "The Door"]
In the last scene where the Night's King enters the cave, while Bran and Three-Eyed Raven are green-sighting into old Winterfell, Meera shouted to Bran to warg into Hodor and wake up.
He did it and warged into the present Hodor, but after a few minutes, when Meera shouts "Hold the Door" we are taken back into the green-sight and there we could see that Hodor is actually staring at Bran and it totally seems like he could see him.
We know what happened later but it is still a mystery whether Hodor saw Bran or not. - If Hodor saw Bran then his entire life (since then) he would have the memory of Bran and he knew Bran's face even before he was born. - When Bran asked Hodor about what happened in the episode "Red Woman", Hodor became sad as if he didn't want to tell what happened.
Was Bran seen by Hodor?