The Binder is a new role added directly to dNethack. Binders are a new type of spellcaster, that conduct rituals and follow special conducts in return for power. They face a difficult early game, though they can eventually achieve great power.
The Binder is based on the class of the same name from the DnD 3.5 Tome of Magic. Tome of Magic Binders were, in turn, based on medieval magical traditions like that found in the Lesser Key of Solomon. The abilities of dnethack Binders are almost completely dependent on which spirits they have bound.
The Convict is a role added in the Convict Role patch, by Karl Garrison. It was designed to be more difficult than Tourist; (statistically the most difficult class in vanilla NetHack), a goal at which it succeeds handily.
Pirates are a melee focused class that may have trouble finding a good weapon. Their first sacrifice gift is the Marauder's Map, and their crowning gift is an artifact cutlass (scimitar), Reaver. Their default pet is either a parrot or a monkey.
The Marauder's Map can be invoked to detect all items and artifacts on the current dungeon level. Pirates don't receive artifacts (other than the Map) as a reward for sacrificing, so they will need to keep their eyes open for good artifacts as they explore the dungeon.
The Noble is a role added directly to dnethack. Humans, incantifiers, and vampires can be Nobles. Nobles are a melee-focused role that specializes in one-handed weapons. They can engage in some spellcasting if their ability scores are good enough.
Nobles begin with a +2 rapier, +1 gloves, and +1 leather cloak. Noblemen start with a ruffled shirt, while Noblewomen start with a set of Victorian underwear. Their starting pet is a saddled pony.
Nobles have an automatic first gift, the Rod of Lordly Might.
Their quest artifact is an artifact opera cloak (vampires) or ornamental cope (non-vampires). Note that this means that the base type of the Noble quest artifact changes from game to game.
Elf Rangers, Noblemen, Priests, and Wizards all receive a single, shared quest, the Elf quest.
Drow Rangers, Rogues, Priests, and Wizards receive a quest based on their gender instead of their role. Once on the quest, they may choose to change alignments and assassinate their quest leader instead of their nemesis.
Drow Nobles receive a more normal quest based on gender.
Worm that Walks
Worms that Walk will be able to take over from dead characters that they run across, and can also occupy and revive monster corpses.
Time Travelers come from a fantasy-future with guns, lasers, lightsabers, and psychic powers. They have damaged immune and digestive systems. If they remove their starting isolation suit they will contract deadly illnesses, and they can't eat food other than tins and potions.
Since I'm planning to add psychic powers, I may as well add a Psion class, right?