Board Thread:Questions and Answers/@comment-24520051-20161120235846/@comment-1257201-20161130225608

Shadzane, if you include characters who simply did not reappear after 1986, that's certainly true. But for all we know, many of them still "exist" even if they were never seen in comics: e.g., Bruce's Aunt Agatha. I was thinking of "erased" in a stronger sense: that we can prove (or strongly argue) that this person does not exist. In the post-Year One world, it's simply not plausible that Alfred has a daughter or that Jason Todd saw Natalia Knight as a "mother figure": if this were true, they would have to have been mentioned at some point.

If Wally's answer doesn't qualify, I would suggest Ardora and Lex Luthor, Jr. -- but maybe they don't count because they actually died before Crisis.