This will be the highest-profile test to date whether big prelaunch online buzz and awareness translates into big ratings. ABC‘s upcoming drama series Marvel’s Agents Of S.H.I.E.L.D. yesterday crossed the 1 million Facebook fans mark, believed to be a record for a new series. A look at the list of the new fall shows with the largest FB following illustrates why the networks are so eager to expand existing franchises or bet on presold titles, like S.H.I.E.L.D., an off-shoot from blockbuster film The Avengers. The No. 2 and 3 new series in number of FB fans are spinoffs: the CW’s The Originals (528,690), which will face off with S.H.I.E.L.D. in the Tuesday 8 PM slot later this fall, and ABC’s Once Upon A Time In Wonderland (498,846). In an indication there is some correlation between online popularity and premiere ratings, Fox’s Sleepy Hollow, which got off to a strong start this week, is No. 4 on the FB fans list with 362,013. (NBC’s Dracula is No. 5 with 215,295). Like Sleepy Hollow, which just got a big Live+3 DVR boost, S.H.I.E.L.D. and the other shows ahead of it on the list appeal to younger audiences who won’t necessarily tune in to watch the show live.