Characters:
Orc Warboss/Big Boss: Generic Orc lord/hero choice. No fancy rules and won't go toe-to-toe with a Chaos Lord but they are cheap at 115/55 points and are also good options for adding some killing power to units.
Savage Orc Warboss/Big Boss: As above but you get
Warpaint for a 6++ and
Frenzy for a bit more damage output. If he is in that Savage Orc horde containing the Shaman and the
Lucky Shrunken Head you are up to a 5++ for free (kind of).
Black Orc Warboss/Big Boss: A good chunk more expensive at 160/90 but they get 1 extra WS and the
Quell Animosity rule, along with the standard Black Orc ones. The internet loves these because they hate animosity and you ignore failed tests for D6 S5 hits with these in units. Handy if you have put too many eggs in too few baskets, and can not afford for a unit to fail an animosity test.
Night Goblin/Goblin Warboss/Big Boss: Super cheap option which can either be employed to add damage output to those big units, or as lone characters on Gigantic Spiders/Wolves/Great Cave Squigs to go War Machine hunting.
Savage Orc/Orc Shaman: Lets you access the
Spells of Da Big Waaagh. Can be mounted on Wyverns or Boars. The Savage variety is often seen sporting the
Lucky Shrunken Head in a horde of Savage Orc Big 'Uns.
Night Goblin/Goblin Shaman: these cast from
Spells of Da Little Waaagh, which quite frankly is not as good, but they are cheaper and offer a second casting option. Especially Night Goblin Shamans, who get a free
Magic Mushroom casting dice to roll, although this can cause you some harm. Very useful for a secondary caster to try and draw out some dispel dice. The Goblin flavour can be mounted on the big spider.
Gigantic Spiders: A 40 point mount upgrade for your Goblins, remember that you are almost better off just sticking a Big Boss on it, because you will get the free wound upgrade from the spider. Adds +2 to your Armour save and provides M7 and all the Obstacle-ignoring rules spiders have along with 3 poisoned S4 attacks. Useful for War Machine hunting/babysitting.
Wyverns: I am not scared of sticking my general on a monster although many people are. Gets you the 18" Ld bubble and allows you to fly. My beef with Wyverns is they cost 160 points and only have 3 attacks each. True they are
Poisoned Attacks and are WS5 S6, plus the
Thunderstomp, but I always feel a little short-changed. Can be useful for sticking an Orc Shaman on, provides some mobility and some extra CC protection at the cost of making him substantially more shoot-able. Fortune favours the brave
Great Cave Squig: Similar to the Gigantic Spider except it costs 50 points and is a little stronger in CC. Also gives the Squig Hoppers a bonus if the Big Boss joins them.
Gorbad Ironclaw: Gorbad is great at killing but not so great at taking damage. He comes in at 375 points but for that he is your BSB & General rolled into one. This is a blessing and a curse, DO NOT ALLOW HIM TO BREAK! He will be instantly removed as per the BSB rules. It does offer you an increased
Inspiring Presence bubble of 18" and he also has his own animosity-removing bubble of 18". He can upgrade as many units to
Big 'Uns as you like. He gets 4
Always Strike First attacks at WS7 S5 (6 in the first round) I5 with no armour saves allowed and
Multiple Wounds (D3). That is a pretty scary proposition. The downside is (and a pretty major one at that) he has no ward save, so you are reliant on his T5 and 3+ AS for protection.
Azhag the Slaughterer: He is super expensive at 550 points as he is pretty beastly in combat whilst also being a Lvl3 Death wizard, which is a super interesting option as there is no other access to this lore. He comes atop his Wyvern (so gets all those benefits mentioned earlier) and gets a 4+ 5++ save from his armour. He hits with 5 attacks, re-rolling misses in the first round of combat, at S5 (6 in the first round). He also allows re-rolls on failed animosity within 18". But 550 points is steep.
Skarsnik & Gobbla: Skarsnik weighs in at 275 points. He comes with some really nice benefits, his
Sneaky Schemes has gimped many people I have faced, delaying units and forcing them to enter as reinforcements on their first turn. Amusing when you delay enemy War Machines etc.
Tricksy Traps is vaguely useful in that it allows rallying Night Goblin units to move and shoot in the turn they rally. His Prodder is pretty sweet, a
Bound spell (5) Magic Missile which does D3 S6 hits, increased to D6 if you are within 12" of a NG horde (which you should be) with no armour saves allowed. Between him and Gobbla he also gets 8 attacks, 4 of which are at S6 with
Killing Blow. The downside is, which is hard to get away from, he has no save besides some Light Armour, so you only have T4 and 6 Wounds for protection. You don't really want him fighting too many hard hitting enemies, definitely have some big bosses for protection and place him on a corner.
Grom the Paunch: Grom is another General come BSB rolled into one. He comes with a Chariot (S5 T4 W3 5+ 5++) which is fairly hardy as chariots go and has WS5 S6
Killing Blow, 5+ 5++ and
Regeneration. All in all I think Grom is pretty decent, he hits hard and has some pretty decent protection as far as O&G go.
Wurrzag: I've never used him but he clocks in at 350 points compared to a normal SO Lvl 4 at 205 points. He is a level 4 caster with an extra spell which can instantly kill enemy wizards within 12", assuming you roll a 6 and successfully cast it. He also has a
Vindictive Glare bound spell and best of all he can store a dice for his power pools, has
Magic Resistance (3) and can re-roll miscast results. Also has a 5++. He is pretty decent but I'm not entirely sure he is worth the cost.
Grimgor Ironhide: I don't know why, but I really don't like Grimgor. Perhaps it is his backstory, he just doesn't do it for me. He is certainly hard as nails though. He must take his Black Orc bodyguard who get +1WS and
Hatred. He hits with ASF at S7 (S8 in the first round), has
Hatred himself so re-rolls, and has a 1+ 5++ save. He is a combat beast and is also pretty cheap at 355 points. Probably one of the better value choices in the Special Characters section.
Snagla Grobspit/Gtilla Da Hunter: Never used these, know little about them. Gtilla has a mediocre bow Magic Item and gives his Wolf Riders +1BS and
Quick to Fire. Snagla has some pretty crappy magic items and allows his Spider Riders to Ambush and have
Devastating Charge. Neither seem especially worth it to me. You can maybe get some utility out of them, particularly the
Ambushers. They are essentially fancy expensive Big Bosses for your throwaway units.
) second-hand stuff can easily be repurposed to be given the weapon options you want them to have (providing you have the bitz available). I recently managed to pick up 20 second-hand Boyz with additional hand weapons that I'm repurposing into Arrer Boyz with some bows from the ancient 5th-6th Edition Night Goblin kit, which have larger, ham-fisted hands that don't look hugely different from Orc hands, glued to Orc arms that had the original hands cut off at the wrist.
I am picking up a little horde, soon-ish, of O&Gs froma friend back in the days..
) but you'll need to convert 4 extra Night Goblins to satisfy the requirement for 1 Gobbo for every 3 Squigs... though with a load of second-hand Greenskins heading your way, I'm sure you'll be able to weed out a few to fit this role 
. In total that unit would reach 32 models in size (24 Squigs plus the 8 Herders - deploying it in 4 ranks of 8 will make a nice big unit that scares the pants off your opponent), giving you a good bit of leg room to take some missile fire before reaching combat, and who could not enjoy seeing one of their enemy's favourite units getting munched by a load of snapping mouths on legs? 
