Is Allison the first regular to be killed in a TV series?
I'm not counting the regular mobsters, like Nitti, although I guess they could count as regulars.
I started watching the Untouchables when the reruns came on after the Tonight Show with Johnny Carson, back around 1972 or so.
The episodes I saw began with most of the screen time for Untouchables between Allison and Rossi. It seemed that Ness was always having Allison and Rossi doing something, or with him most of the time, and the others only part of the time.
So when I saw Allison gunned down in an episode, it was a shock. I had never seen a TV series regular killed off before.
While Nitti was killed in an episode, they brought him right back, so I wasn't sure what to make of that.
Now go away, or I shall taunt you a second time.