Grenadier made quite a few undead other creatures in the 80s. Orcs, dwarves, wererats, dragonmen, centuars and others. They're nominally 25mm but the dwarves are oversized and a robust 28mm scale. Ral partha made some excellent undead hounds.
Here are two dwarves with an orc (left) from a recent ebay lot.
There is undead minotaur from the Chainmail range which is easy and cheap on ebay as well. More undead hounds too.
Another vote for the mordheim ones, they are really great. Was lucky to grab them from the bits service back in the day just before it went caput (and my patronage of GW products for good with it, so long dudes). I bet they'd cost you dearly on ebay now.
As for putting them in my own fantasy worlds, I like to think anything other than human is far less restless and much more difficult to raise. The necromancer responsible has to be very skilled and dedicated, and the results are usually one-offs or small batches. Otherwise I'd be tempted to make encounter groups of each kind and fall deeper into lead madness.
And in D&D elves and related fey have no souls and so can't be reanimated, and this is a rule easy to import into any other setting, and/or extended to include whatever else you can't be bothered to collect in zombie or skeleton varieties. I'm tempted to say only humans have souls and have a chance at all but I already have a bunch of the above grenadier ones, hence I'm just going with "far less restless" per above.