Phryne Fisher (phrynefisher) is the one who'd be most connected to Jack as a fellow Clandestine Field Agent. She's from 1920s Melbourne and is amazing. She likes to flirt, sleep around, have fun and solve crimes.
Otherwise I have Minerva McGonagall (minamcgonagall) (pre-series 1950s, been teaching for a couple of years), Maria Hill (post CA:TWS), Luke Skywalker (luke_skywalker, engineer) & Elizabeth Weir (elizabethweir, interpretor)