Tina Fey as Liz Lemon, James Marsden as Criss. (NBC/ALI GOLDSTEIN/NBC)

That same Thursday night of the “30 Rock” series finale, NBC will toss struggling newsmag “Rock Center with Brian Williams” from the net’s once glorious Thursday 10 p.m. timeslot (and home to “ER”) to move in an actual scripted drama series — and a doc drama at that.

Jekyll/Hyde-ian “Do No Harm” follows a highly respected neurosurgeon named Dr. Jason Cole who has an alter ego named Ian Price.

 Ian is a nasty piece of work. Dr. Cole has been keeping Ian in check with regular doses of a powerful experimental drug.

 But Ian has developed a work-around to the drug, and now plans to make up for all those years he was not able to step out high wide and plentiful.

 “Rock Center” meanwhile, is being shipped off to Fridays at 10, starting Feb. 8, following “Dateline.”