Another members of the world famous Hong Kong Cavaliers. From World Watch Online:
Real name unknown, believed to have met Buckaroo at Phillips Exeter, but may be only self-taught with a grade-school education acquired in the South. Young, handsome, of good family. Vain, pleasure-loving, heartless, sordid, callous and sentimental, he can be brave to excess or [...]

Another in the list Buckaroo Banzai’s companion and member of the Hong Kong Cavaliers. From World Watch OnLine:
Real name unknown, of Latin extraction. Dark, moody, dangerous, although possessing an easy grin and a quirky artistic streak. Fond of bright, flashy colors. Executes bold pencil sketches of Buckaroo and the Cavaliers which he sells to national [...]

Here is an NPC to use in your D20 system, Rawhide, one of Buckaroo Banzai‘s companions and member of the Hong Kong Cavaliers.
PCGen Version: Rawhide.pcg (right click and save as to download)
PDF Version: Rawhide.pdf
Bookmark on Delicious Digg this post Recommend on Facebook share via Reddit Share with Stumblers Tweet about it Subscribe to [...]

Who doesn’t know of the great scientist and surgeon, Dr. Buckaroo Banzai? Here is a D20 version of him to use as an NPC. Perhaps your characters run across him accidentally while investigating an alien artifact? Maybe they end up joining the Blue Blaze Irregulars to find out information about a specific crime family?
PCGen Version: [...]

The Runic Fellowship is a group adventurers that have been working together for many years.
Vyecheslav, male human Drd11: CR 11; Size M (5 ft., 2 in. tall); HD 11d8; hp 58; Init +1 (+1 Dex); Spd 30 ft.; AC 11 (+1 Dex); Attack +9/+4 melee, or +9/+4 ranged; SV Fort +7, Ref +4, Will +10; [...]

The pirates ship is a converted merchantman crewed by 30 pirates. A pair of oars on each side gives it maneuverability against the wind.
Pirate Leader
Name Green-Eye Razicad, the Dwarven Pirate Alignment: Neutral evil Gender: Male Race: Dwarf Height: 4′ 2; Weight: 185 lbs Strength: 20 (+5) Dexterity: 14 (+2) Constitution: 17 (+3) Intelligence: 10 (+0) [...]

Desolate areas are wild caves and tunnels that are not settled and generally do not support much in the way of wildlife or monsters. Much of the Lowerdark is desolate.
Aboleth
Aboleth slaver brood
Annihilator
Avolakia
Behir
Beholder
Beholderkin (deathkiss or gouger)
Bodak
Cloaker mob
Cloaker, shadowcloak elder
Cockroach, giant
Deepspawn brood
Delver
Desmodu
Dragon, mature adult deep
Dragon, mature adult copper
Dragon, very old black
Dragon, mature adult red
Dragon, mature adult shadow
Drow [...]

Lowerdark wilderness areas are wild caves and tunnels that are not settled but still support significant wildlife or monsters.
Aboleth
Aboleth slaver brood
Annihilator
Avolakia
Behir
Beholder
Beholderkin (deathkiss or gouger)
Bodak
Cildabrin
Cloaker mob
Cloaker, shadowcloak elder
Cockroach, giant
Desmodu
Delver
Dragon, adult deep
Dragon, adult copper
Dragon, old black
Dragon, adult red
Dragon, adult shadow
Drider
Drider, vampire
Drow patrol
Duergar raiders
Deepspawn & spawn
Earth Glider
Fiendwurm
Fomorian
Giant, stone
Gloura
Grimlock hunters
Gray render
Hound of the gloom
Illithidae (any)
Knell beetle
Kuo-toa war party
Lurker
Lurking strangler
Maur
Mind [...]

Settled areas feature colossal caverns that can be miles on a side, a number of small villages and vaults no more than a day or two travel from each other, and some tunnel patrols from nearby cities or fortresses. Patrols are most often Drow, Illithid Thralls, Duergar, or Derro.
All-consuming hunger
Barghest
Bat, deep (sinister)
Behir
Chitine hunters
Cildabrin
Cloaker
Deepspawn & spawn
Derro [...]

Possible list of encounters in the Frontier areas of the Underdark. Frontier areas are lightly settled tunnels or caves, but communities are small and far apart, usually separated by miles of tunnels. Occasional larger forts maybe present to give warning to larger settlements in the distance.
Abishai, black
Ankheg
Baphotaur
Bat, deep
Baneguard
Beholder, gauth
Bodak
Bugbear band (hunters, scouts, family group)
Chitine hunters
Cildabrin
Cloaker
Cockroach, [...]