Dexter: Original Sin gives more of a background to Dexter Morgan, one of the best TV antiheroes of all time. Now, Dexter‘s most iconic villain may get his own, much-anticipated spin-off series. While each season of the original Dexter TV show had its own “big bad,” few are more memorable or chilling than Arthur Mitchell, a.k.a. The Trinity Killer, played by John Lithgow. Of all the villains in Dexter, The Trinity Killer appeared to be the only one who was able to get to Dexter, killing Rita in one of the best Dexter episodes of all time.

https://screenrant.com/dexter-origina-sin-vicky-noonan-reference-trinity-killer-prequel-setup-explainer/