Here are the pets which are currently listed in the pet journal of the beta as well as the ones we know about. As always, you can expect this list to change as more info comes in and I can flood the post with accompanying images.

Profession

Ancient Nest Guardian – Arch
Frostwolf Ghostpup – Arch

Lil’ Leftovers - Cooking

Lifelike Mechanical Frostboar – Eng
Mechanical Axebeak – Eng
Mechanical Scorpid – Eng
Sky-Bo – Eng

Nightshade Sproutling – Herbalism
Ore Eater – Mining

Soul of the Forge - Blacksmithing

Soul of the Forge – Blacksmithing

Elekk

Elekk Plushie – Tailoring

Reward

Ghastly Kid – Quest: Mastering the Menagerie
Albino Chimaeraling – Quest: Mastering the Menagerie
Firewing – Quest: Mastering the Menagerie
Nightfeather Hatchling – Quest: Mastering the Menagerie
Puddle Terror – Quest: Mastering the Menagerie
Shadeback Hatchling – Quest: Mastering the Menagerie
Sun Sproutling – Quest: Mastering the Menagerie
Sunfire Kaliri – Quest: Mastering the Menagerie
Weebomination – Quest: Mastering the Menagerie

Everbloom Peachick – Quest: For the Birds
Iron Starlette – Faction specific quest in Blasted Lands
Sentinel’s Companion – Quest: Little Sister Lost

Ikky

Ikky – starts from Ikky’s Egg in Shadowglade, Spires of Arak

Digrem Orebar
Meadowstomper Calf – starts from Digrem Orebar, Ring of Trials.

Wild Pets

Gnawtooth Rat – Garrison
Pygmy Cow – requires Level 3 Barn, Garrison
Bloodsting Wasp
Bloodthorn Hatchling
Bone Serpent

Moonshell Crab

Shadowmoon Valley

River Calf
Flat-Tooth Calf
Axebeak Hatchling, Bloodbeak, Junglebeak
Sapphire Firefly, Swamplighter Firefly, Violet Firefly, Waterfly
Cerulean Moth, Crimsonwing Moth, Royal Moth
Brilliant Bloodfeather
Golden Dawnfeather
Icespine Hatchling, Mossbite Skitterer, Thicket Skitterer
Fen Crab
Frostshell Pincher
Ironclaw Scuttler
Kelp Scuttler
Zangar Crawler
Sky Fry
Dusty Sporewing
Glowing Sporebat
Shadow Spoebat

Achievement

Royal Peacock – Draenor Pet Master
Molten Corgi – Feat of Strength: WoW’s 10th Anniversary
Stormwing – So. Many. Pets
HogsVictory in Hillsbrad

Drop

Amberbarb Wasp, Twilight Wasp, Wood Wasp
Bronze Whelping – Iron Horde, Blasted Lands
Eye of Observation – Omoro the Observer, Taladar
Servant of Demidos
Lanticore Spawnling – rare in UBRS
Dwarf Gronnling
Runtish Gronnling

Doom Bloom

Doom Bloom – inside a cave in Steamscar Rise, Gorgrond

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Fruit Hunter – Wiggling Egg, Grom’gar

Hydraling - Varasha's Egg, Spires of Arak

Hydraling – Varasha’s Egg, Spires of Arak

Grovestrider Hatchling

Teroclaw Hatchling – Teroclaw Nest

Sproutlings

Autumnal Sproutling, Forest Sproutling, Kelp SproutlingSassy Sproutling

Brilliant Spore, Crimson SporeUmbrafen Spore

Stonegrinder

Stonegrinder – Chest inside a motion sensor cave (Orunai Coast)

Zomstrok - Darktide Husk and Boneshell, Shadowmoon Valley

Zomstrok – Darktide Husk and Boneshell, Shadowmoon Valley

World Event

Bush Chicken
Mystical Spring Bouquet
Lovebird Hatchling

Stout Alemental
Cursed Birman
Widget the Departed
Blazing Cindercrawler

Vendor

Kaliri Hatchling

Kaliri Hatchling – sold by Vesharr

Rubyfeather

Rubyfeather – sold by Vesharr

Bone Wasp – Revered with Laughing Skull
Draenei Micro Defender – Revered with Council of Exarchs
Frostwolf Pup – Revered with Frostwolf Orcs
Albino River Calf – Revered with Steamwheedle Preservation Society
Forest Sproutling – Revered with Steamwheedle Preservation Society
Son of Sethe – Revered with Outcast Arakkoa

Crazy Carrot – requires Herb Garden (1000 Seeds)
Sea Calf – requires Fishing Shack, rep with Nat Pagle (follower) and 50 Lucky Coins
Land Shark – requires Fishing Shack, Good friends with Nat Pagle (follower) and 50 Lucky Coins

Unknown

Temporal Shard
Echo of Murmur
Limbflayer

This list is subject to change