Originally Posted by
ohfellow
Cass did have the longest running Batgirl book, 73 issues, and then a 6-issue mini-series.
Barbara had a 52-issue run, then a 50-issue run, so that is more issues, but split into 2 eras (New 52 and then Rebirth).
(I'm not counting Annuals, so the exact totals are a little different.)
As for number of years serving as Batgirl total, it would probably be Barbara, but I'm not sure, since she was Oracle for a long time. I don't have the chronology in my head, but I'm sure others here know it.