Marvel's Luke Cage: 44 Easter Eggs You Probably Missed
5. The Punisher
The Punisher would have been a great addition as a cameo in Luke Cage, but he wasn't called on unfortunately.
He did get a reference though.
In episode 11, DA Tower brings him up in reference to the potential damage the new Judas weaponry could do: "Frank Castle shot the city to hell, imagine what he could do with one of these things."
Tower of course was key in bringing Castle to justice in Daredevil season 2.