I put together a couple of thematic hero groups. It’s fun, and I’m sure I’ll come up with some more. Enjoy!? 
Friends (and Forces) of Nature
- Alexstrasza
- Brightwing
- Illidan (Shan’do)
- Lunara
- Malfurion
- Ragnaros
- Rehgar
- Rexxar
- Thrall
- Tyrande
Halloween’ers (Trick or Treat!)
- Abathur ( Pajamathur, Skelethur)
- Alarak (Herald of N’Zoth)
- Alexstrasza (Wyrm)
- Artanis (Shogun)
- Arthas (Count)
- Auriel (Demonic, Spirit Healer)
- Brightwing (Bewitching, Flying Monkey)
- The Butcher (esp. Spectral)
- Cassia (Goddess, Pirate Queen)
- Cho // Gall
- Chromie (Creepie, Genie)
- Diablo (esp. Chamuco)
- Falstad (Buccaneer)
- Gazlowe (Big Top)
- Greymane
- Jaina (Dreadlord)
- Johanna (Centurion)
- Kael’thas (Stormbot)
- Kel’Thuzad
- Kerrigan (Cheerleader, Countess)
- Leoric
- Li Li (Shadowblade)
- Li-Ming (Star Princess)
- The Lost Vikings (Pajama Party)
- Lt. Morales (Apothecary)
- Mal’Ganis
- Malthael
- Muradin (Mauradin’)
- Murky (Funny Bunny, Garden Shambler)
- Nazeebo (Harlequin)
- Nova (Novazon)
- Orphea (Hallowed Orphea)
- Sonya (Death Knight)
- Stitches
- Stukov (Reef Admiral)
- Sylvanas
- Tassadar (Crypt King)
- Tracer (Divine Herald)
- Tychus (Infested)
- Tyrande (Eagle Eye, Love Goddess)
- Uther (Lumberjack)
- Valeera (Vampire Slayer V)
- Valla (Angelic, Deputy)
- Whitemane (Witch, Showstopper)
- Xul (Scarecrow, Serpent King)
- Yrel (Jester)
- Zagara (Desert Queen)
- Zarya (Phantom Knight)
- Zeratul (Ronin, Unraveler)