There's also an Achievement reward pet from Stormstout Brewery: Hopling
It's a reward from Ling-Ting's Herbal Journey. Here's a link to the comments on Wowhead for the achievement. It also offers a workaround for the one that might be bugged beneath the stairs. For that one it'd be best to wait until the instance is clear. Or, since you'll be heading out to the Timeless Isle anyway, drop by the Valley of the Four Winds on your max-level character for an easy clear, and easy pet!
2. Hallow's End Begins 18 October!
Here is the link to our article on how to collect all the Hallow's End pets, except Arfus
That said, here's the list of all the pets you can collect!
3. Squirt in the EU Garrison 24 October & KR / TW Garrison on 25 October
Squirt the Wandering Trainer will be in EU Garrisons on 24 October & KR / TW Garrison on 25 October. Our strategies for this leveling event can be found here.
4. Hallow's End Pack until 31 October!
Celebrate Azeroth’s spookiest season with this menacing menagerie of mounts and pets! Get it before all items included in the bundle leave the Shop soon (31 October 2023).
If you already have one or more items from The Hallow's End Pack available in your Collection, its price will automatically adjust. All items from The Hallow’s End Pack are also available as standalone purchases.
The pets that can be collected from this pack are:
Ysergle is included in both the EPIC PACK ($29.99 USD) & LEGENDARY PACK ($49.99 USD). Nothing I could find indicated when these packs might leave the shop, as the only thing from the packs with a time limit was the discount code for the gear store. If that changes, we'll add it to our weekly news!
8. Zipao Tiger Pet Available as Prime Gaming Reward until 24 October
The Zipao Tiger pet is now available from Prime Gaming from today until October 24th! This was previously available from the Recruit-A-Friend program.
9. Lil' Maggz in the Shop until 31 October
What’s more adorable than a Pit Lord? A baby Pit Lord! Take this adorable prince of Outland everywhere you go when you adopt him from the Battle.net Shop for $10 USD—now available for a limited time.
Lil’ Maggz leaves the Battle.net Shop indefinitely on October 31 and will arrive in a future rotation of the Trading Post, but no sooner than three months after the pet leaves the Shop.
10. October Trading Post
October brings a new batch of Trading Post items, and among them is a previous store pet: Lil' K.T.!