Jonni DC, Continuity Cop is a force of the DC Universe. After the Crisis of Infinite Earths, countless old characters survived whose presence did not fit wel in the new, unified DC Universe. Jonni DC was created with the role of locating and eliminating all such characters. She was killed while confonting Darkseid in her second appearance. She has since returned to work and killed again. Unlikely to remain dead for long.
For a Continuity Cop, her victim list has created some continuity conundrums of its own. Victims such as Cecil Sunbeam of the Green Team have turned up alive again without explanation. However, in the last issue of the Ambush Bug: Year None miniseries, she had risen again, this time as a Black Lantern. Oddly enough for a character possessed by a black ring (or rather, fitting in with her own disparate nature), she was not controlled by the ring, rather much like her own depressed self.