Hello I could use some advice on what would be good base class before going into Hell Knight in the Hell's Vengeance Campaign. The character believes himself a servant of the Cheliaxian law willing to do what it takes to keep order, like Judge Dredd. He looks to the order of Hell Knights as inspiration and whishes to become one. I was gonna do a Anti-Paladin(Tyrant) but that just feels to self serving, something I'm not looking for. I could use help in finding ideas that go along with my concept and fit the campaign.
On a side note is the cavalier a viable class for this campaign?
I'm not very familiar with Judge Dredd outside of knowing he exists. As for making an aspirant Hellknight for Hell's Vengeance, I really can't recommend picking up the fantastic Path of the Hellknight book. It goes into detail on the hellknights, adds some new abilities and archetypes, and even features the Order of the Ennead star, which works perfectly for a cavalier aspiring to be a Hellknight.
As for whether a Cavalier works well in Hell's Vengeance or not (presumably concerning whether to have a mount or not), the cavalier features a number of archetypes that either trade out the mount or put less focus on it in exchange for interesting class features, such as the castellan, constable, honor guard, and huntmaster, among others.