Aside from the big cosmic heavy hitters like The Monitors, Perpetua, Mr. Mxy, and Sandman, who in the DCU actually know that their lives have been manipulated and revised by outside forces?

Lois & Clark certainly know their history was altered, although Jon's memories of his time shenanigan-steeped childhood seem to have been wiped.

Batman certainly knows, thanks to his exploits with The Flash in The Button, and Superman letting him know about what happened to him.

Wonder Woman knows because Supes & Bats have tipped her off about their respective experiences and she knows from The Lies that her own memories of the past are unreliable.

Per Doomsday Clock, Lex Luthor seems to have a better idea than any of them in terms of just how much their lives have been regularly altered by time shenanigans revising their history. Hell, he seems so aware of how precarious reality all is that he even readied a backup of himself from Earth-38 just in case things go cockeyed again. There's no doubt that the smartest man in the DCU knows how to plan ahead.

Barry knows, although not to the same degree that Wally does, although his exact memories seem to be a mish-mash of both timelines now. Wallace seems vaguely aware, but only in the sense that he knows he didn't exist prior to the most recent reboot. Iris seems to have all her memories back, which makes sense given how much time shenanigans have been at play in her life from the very beginning.

Hal Jordan, thanks to being in the Anti-Matter Universe when the Multiverse was recreated as a single universe during the original Crisis, was aware that history had been rewritten, along with everyone else present at that battle on Qward, like John Stewart and Kilowog (whose entire planet was retconned away). This knowledge certainly played a major part of Hal's later actions as both Parallax and The Spectre. However, Johns pointed out that a lot of Hal's memories of those times were stripped away from him when he was resurrected during GL Rebirth. In any case, the Guardians have just made Hal aware that history was rewritten by someone when they showed him the Book of Oa in Morrison's first issue of The Green Lantern.

Currently, it seems The Spectre himself is unaware of being rebooted, since he's back to being Jim Corrigan again with seemingly no awareness of his decision to move on during the conclusion of Ostrander & Mandrake's run.

Rene Montoya looks like she's being let in on the secret after she confronted Lois with what's going on with Vic Sage suddenly being alive again, despite both of them remembering him dying in Nanda Parbat during Fifty-Two.

Anybody else?