One of the most enjoyable 4E combats we have had involved a party of four level 10 PCs - half-elf bard, eladrin wizard, human barbarian, and dwarf fighter - leading a small army against a small orc horde.
The best part, of course, was when the PCs had to fight their way through their section of the battlefield and take out three of the key orc leaders.
I only used three stat blocks which I am posting here. The most basic orc was this one to the left: it's the minion version of my bog-standard orc which is a level 1 brute. (I go back to AD&D and reduce monster levels to match their 1E hit dice. It suits my game better, particularly as we're not going to Epic.)
The critical damage may look high but I "bought" it by trading 1 point of damage from its normal attack and having a 20% chance that a critical would trigger dealing 5 extra damage (20% = 1/5; reciprocal of 1/5 is 5 and 5 x 1 = 5). I like my 4E brutes to have big swings in the damage they can potentially deal and this seemed to be the best way to model that with a minion.
I really liked the stat block in Monster Vault: Threats of the Nentir Vale for a swarm of orcs, albeit referred to as a throng. I stole it and made only a few changes to suit my tastes but this is essentially the Bloodspear savage throng from that book.
I found these swarms to be an interesting complement to the orc minion above, and fairly handy as a damage soak for the orc leaders.
And that's the last of these stat blocks: the orc battlethane. I admit that the choice of weapon - a broadsword - was odd for an orc, but I wanted to use some orc miniatures that I had - orc eye of Gruumsh - so went that rather non-orc-like weapon. How I wish I had the orc with a double-axe instead....
OK, so battlethane sounds like one of those odd portmanteaus that 4E was famous for - the idea for which, I think, was stolen from Magic: the Gathering (I've never played MtG so I am only guessing) - but I wanted battle rather than war (such as warchief) to reflect the fact that these are not actually the leaders of their clans or tribes. These orcs are here in The Crags near Neverwinter for a reason that is explained in <this post> but they're not the true leaders of the orc horde which is no longer going to be formed thanks to the deeds of the PCs.
So, name aside, I like the way this stat block turned out. I've experimented with mechanics involving marks - one of my favourites is <this one> - but this one worked really well and seemed to reflect the nature of the orcs. The other challenge was to create an appropriate leader power and I thought Thane's Cry for Blood was, again, very orc-flavoured. And with so many monsters on the board, it seems I may have had a chance or two to use it....