Somebody asked me not to make an everybody-can-do-everybody else kind of list, and that convinced me. Not only is it more practical, but it is also simpler. Remember, this doesn't include the more specific hybrids like half-fiends and whatnot. Just the basics. What do you think of this:
--Laying Down The Law--
Humans can mate with humans, elves, dwarves, gnomes, halflings, orcs, goblins, ogres, and trolls.
Elves can mate with humans, elves, dwarves, gnomes, halflings, goblins, ogres, and trolls.
Dwarves can mate with humans, elves, dwarves, gnomes, and halflings.
Gnomes can mate with humans, elves, dwarves, gnomes, and halflings.
Halflings can mate with humans, elves, dwarves, gnomes, and halflings.
Orcs can mate with humans, orcs, goblins, ogres, and trolls.
Goblins can mate with humans, elves, orcs, and goblins.
Ogres can mate with humans, elves, orcs, ogres, and trolls.
Trolls can mate with humans, elves, orcs, ogres, and trolls.
--The Humanoid Hybrid List--
21 Hybrids In All (22 if you count the Orog):
Half-Elf
Half-Dwarf
Half-Gnome
Half-Halfling
Half-Orc
Half-Goblin
Half-Ogre
Half-Troll
Dwelf
Gnelf
Elfling
Nain
Nibelung
Lovar
Duende
Hobyah
Risi
Ferrishyn
Fenoderee
Ogrillon or Orog
Trow
--The Hybrid Formulas--
Hybrid Mainstream Races:
HUMAN
Human + Human = Human
Human + Elf = Half-Elf
Human + Dwarf = Half-Dwarf
Human + Gnome = Half-Gnome
Human + Halfling = Half-Halfling
Human + Orc = Half-Orc
Human + Goblin = Half-Goblin
Human + Ogre = Half-Ogre
Human + Troll = Half-Troll
ELF
Elf + Human = Half-Elf
Elf + Elf = Elf
Elf + Dwarf = Dwelf
Elf + Gnome = Gnelf
Elf + Halfling = Elfling
Elf + Goblin = Duende
Elf + Ogre = Risi
Elf + Troll = Ferrishyn
DWARF
Dwarf + Human = Half-Dwarf
Dwarf + Elf = Dwelf
Dwarf + Dwarf = Dwarf
Dwarf + Gnome = Nain
Dwarf + Halfling = Nibelung
GNOME
Gnome + Human = Half-Gnome
Gnome + Elf = Gnelf
Gnome + Dwarf = Nain
Gnome + Gnome = Gnome
Gnome + Halfling = Lovar
HALFLING
Halfling + Human = Half-Halfling
Halfling + Elf = Elfling
Halfling + Dwarf = Nibelung
Halfling + Gnome = Lovar
Halfling + Halfling = Halfling
ORC
Orc + Human = Half-Orc
Orc + Orc = Orc
Orc + Goblin = Hobyah
Orc + Ogre = Ogrillon or Orog
Orc + Troll = Fenoderee
GOBLIN
Goblin + Human = Half-Goblin
Goblin + Elf = Duende
Goblin + Orc = Hobyah
Goblin + Goblin = Goblin
OGRE
Ogre + Human = Half-Ogre
Ogre + Elf = Risi
Ogre + Orc = Ogrillon or Orog
Ogre + Ogre = Ogre
Ogre + Troll = Trow
TROLL
Troll + Human = Half-Troll
Troll + Elf = Ferrishyn
Troll + Orc = Fenoderee
Troll + Ogre = Trow
Troll + Troll = Troll
I worked hard to make an accurate and believable list, but criticism is appreciated. I know some of the creatures here you may not have even heard of, and I would be more than happy to give you background info. I was originally tempted to call them things like "Dwogre" and "Trelf", but trying to do that with all of them just sounds silly and lazy.
--Laying Down The Law--
Humans can mate with humans, elves, dwarves, gnomes, halflings, orcs, goblins, ogres, and trolls.
Elves can mate with humans, elves, dwarves, gnomes, halflings, goblins, ogres, and trolls.
Dwarves can mate with humans, elves, dwarves, gnomes, and halflings.
Gnomes can mate with humans, elves, dwarves, gnomes, and halflings.
Halflings can mate with humans, elves, dwarves, gnomes, and halflings.
Orcs can mate with humans, orcs, goblins, ogres, and trolls.
Goblins can mate with humans, elves, orcs, and goblins.
Ogres can mate with humans, elves, orcs, ogres, and trolls.
Trolls can mate with humans, elves, orcs, ogres, and trolls.
--The Humanoid Hybrid List--
21 Hybrids In All (22 if you count the Orog):
Half-Elf
Half-Dwarf
Half-Gnome
Half-Halfling
Half-Orc
Half-Goblin
Half-Ogre
Half-Troll
Dwelf
Gnelf
Elfling
Nain
Nibelung
Lovar
Duende
Hobyah
Risi
Ferrishyn
Fenoderee
Ogrillon or Orog
Trow
--The Hybrid Formulas--
Hybrid Mainstream Races:
HUMAN
Human + Human = Human
Human + Elf = Half-Elf
Human + Dwarf = Half-Dwarf
Human + Gnome = Half-Gnome
Human + Halfling = Half-Halfling
Human + Orc = Half-Orc
Human + Goblin = Half-Goblin
Human + Ogre = Half-Ogre
Human + Troll = Half-Troll
ELF
Elf + Human = Half-Elf
Elf + Elf = Elf
Elf + Dwarf = Dwelf
Elf + Gnome = Gnelf
Elf + Halfling = Elfling
Elf + Goblin = Duende
Elf + Ogre = Risi
Elf + Troll = Ferrishyn
DWARF
Dwarf + Human = Half-Dwarf
Dwarf + Elf = Dwelf
Dwarf + Dwarf = Dwarf
Dwarf + Gnome = Nain
Dwarf + Halfling = Nibelung
GNOME
Gnome + Human = Half-Gnome
Gnome + Elf = Gnelf
Gnome + Dwarf = Nain
Gnome + Gnome = Gnome
Gnome + Halfling = Lovar
HALFLING
Halfling + Human = Half-Halfling
Halfling + Elf = Elfling
Halfling + Dwarf = Nibelung
Halfling + Gnome = Lovar
Halfling + Halfling = Halfling
ORC
Orc + Human = Half-Orc
Orc + Orc = Orc
Orc + Goblin = Hobyah
Orc + Ogre = Ogrillon or Orog
Orc + Troll = Fenoderee
GOBLIN
Goblin + Human = Half-Goblin
Goblin + Elf = Duende
Goblin + Orc = Hobyah
Goblin + Goblin = Goblin
OGRE
Ogre + Human = Half-Ogre
Ogre + Elf = Risi
Ogre + Orc = Ogrillon or Orog
Ogre + Ogre = Ogre
Ogre + Troll = Trow
TROLL
Troll + Human = Half-Troll
Troll + Elf = Ferrishyn
Troll + Orc = Fenoderee
Troll + Ogre = Trow
Troll + Troll = Troll
I worked hard to make an accurate and believable list, but criticism is appreciated. I know some of the creatures here you may not have even heard of, and I would be more than happy to give you background info. I was originally tempted to call them things like "Dwogre" and "Trelf", but trying to do that with all of them just sounds silly and lazy.