Collectively the cats are Monsters, or Fuzzies.
Both my dogs are female, so they’re “the girls.” They respond to this, too.
When combined with my MIL’s two “girls” or my SIL’s two “boys,” they become “the traveling dog park.” (Not within earshot of the dogs, though)
Two JRT’s. Their official title is “The Supervisors.” Often referred to as doglets, puppies, the girls (Even though one is a male. The female is waaayyy alpha, so the feminine is the default gender.)
We have 2 cats, 2 dogs, 2 birds, a guinea pig, and a fish.
When calling the dogs to go out, we yell for the “puppies” (as in “puppies, want to go out?” or “puppies, want to eat?”) even though they are both full grown and over 110 lbs each. When we want to feed the cats, we say “here kitty kitty” which gets both of them running. The other pets don’t really respond much when you call them.
When referring to all of them together, we generally say “the pets” or “the zoo”.
Usually “The Mutts,” “The Demons,” or “The Hellhounds.”
Oh yeah, and when they’re all intertwined together on the couch or bed in such a way that you can’t tell where one ends and the other begins, I like to call them “the Gekittle”.
The kids.
I don’t have multiple pets, but my friend refers to her two rather goofy dogs as Nit & Wit. When she had three, they were Nit, Wit, and Twit. Always liked that.
Incidentally, if I’m actually addressing them (which isn’t as rare as it maybe should be, but at least I’m not actually expecting them to reply), I’ll just collectively call them, “Ladies”, as they’re all female (well, on a chromosomal level, anyway).
We just call them “pets”. As in “Pets!!! Stop fighting!!!”
We have a male cat and a female dog and they fight like brother & sister. Very entertaining but also annoying at times. Other than a few broken cat whiskers, so far there have been no injuries.
Our main cat is named Mung-Chi; the backup kitty is named Ool-Bo.
Collectively, I refer to them as “Mool”… Korean for “water”. 
Four dogs, four cats. Collectively, The Pack. Thus, when I call home and talk to mr.stretch I ask “How’s The Pack?”
The four dogs are also The Pack or the girls, puppies, poodles (though none of them are poodles), monsters, troublemakers, furbears, and fur bearers.
The cats are the boys…and Sybil (3 males, one female). Thus, “Where are the boys (pause) and Sybil?”
We have five cats, who are referred to variously as:
- the kids
- the furballs
- the livestock (as in, “Did you feed the livestock yet?”)
- the boys (the two Singapura boys)
- the girls (the tabby girl and the two Russian Blue girls)
- the kittens
- the kee-tens
- the babies
- the cat-creatures
- the fuzzbuckets
- the princesses (the Russian Blues, who are sisters)
We also have a gecko, but he’s usually just “the gecko,” and doesn’t get lumped in with the cats (who all find him fascinating and potentially tasty)
:dubious:
8 cats, 4 male and 4 female:
Heathens
Monsters
Furbabies
Terrorists
Love Sponges
Little Rotters
The kidder-cats
When it was just one cat and one dog, it was “the girls”, then we got a boy cat, so it became the kids. Depending on who is in the room, it changes between boys, orange kids (girl dog and boy cat, both orange), the greys (boy cat and girl cat both grey tabby) or just the kids.
When I come home from work and four sleepy faces greet me at the door, it’s always “hey kids!”.
I have a dog and a cat.
They are:
people
the zoo
ladies :dubious:
“The fuzzies” covers all 5 of our cats
The two oldest, a brother-sister pair that are both tiger-striped (more or less) are referred to as “the grey ones”.
The two youngest, even though they’re now over 2 years old are “the kittens”.
And the one in the middle is “the calico”, because, well…she is the calico! 
Two cats, one hedgehog. Used to have a fish until he became the ex-fish.
Fuzzy little bastards.
Roomies.
Cats.
Individually, they get pet names. I think they know their given names – at least they know who’s being yelled at. And they know “FOOD TIME!”
The hedgehog is generally called ‘little guy’.