Should I mention Zombo, Harry Angel and Tharg now being part of the Dredd-verse or is that going too far...?
Well spotted, that Squaxx. I'd forgotten the Zombo / Angel / Dredd crossover.
By the time you follow that back to Armoured Gideon's Book III (The Collector), which also featured Angel, you can also include (at least) the following: Bill Savage, Blackhawk, Sam Slade, Abelard Snazz, Shako, The V.C.s, MACH Zero, Wolfie Smith, Harry Twenty, Nick Stone, Dan Dare, Ace Garp, Matt Tallon, Captain Klep, Agent Rat, Robot Archie and Rick Random.
Oh, and Dredd (or a Judge) also shows up in the third book of Skizz.
Were there any judges at the party in Nikolai Dante's last outing?