Update:

>> In terms of 64-bit ARMv8 (AArch64) cores/microarchitectures,
>> there exists or has been announced so far: [...]

This is the most recent list:

- Cortex-A34, Cortex-A35, Cortex-A53, Cortex-A55, Cortex-A57, Cortex-A65(AE), Cortex-A72, Cortex-A73, Cortex-A75, Cortex-A76(AE), Cortex-A77, Cortex-A78(AE|C), Cortex-R82, Cortex-X1, Neoverse E1, Neoverse N1 and Neoverse V1 from Arm Holdings
- Cyclone, Typhoon, Twister, Hurricane, Zephyr, Monsoon, Mistral, Vortex, Tempest, Lightning, Thunder, Firestorm, Icestorm, Avalanche and Blizzard from Apple
- Mongoose M1, Mongoose M2, Meerkat M3, Cheetah M4 and Lion M5 from Samsung
- Kryo 100, Falkor, Saphira and Oryon (Phoenix) from Qualcomm
- Denver, Denver2 and Carmel from Nvidia
- ThunderX, ThunderX2, ThunderX2T99 (Vulcan) and ThunderX3 (Triton) from Marvell
- Potenza, Potenza+, Potenza++ and AmpereOne from Ampere
- Xiaomi FTC310, Xiaomi FTC660, Xiaomi FTC661, Xiaomi FTC662, Xiaomi FTC663 and Xiaomi FTC664 from Phytium
- A64FX from Fujitsu
- TaiShan v110 and TaiShan v120 from HiSilicon/Huawei

(Note that announced but scrapped cores (like AMD's K12) have been removed from the list.)

In terms of ARMv9 cores/microarchitectures, there have been announced so far:

- Neoverse N2, Neoverse V2, Cortex-X2, Cortex-X3, Cortex-X4, Cortex-A510, Cortex-A520, Cortex-A710, Cortex-A715 and Cortex-A720 from Arm Holdings
- Everest and Sawtooth from Apple


Edit: added Avalanche and Blizzard
Edit2: added Cortex-X3 and Cortex-A715
Edit3: added Everest and Sawtooth
Edit4: added Neoverse V2
Edit5: added Oryon
Edit6: added Xiaomi FTC310 and FTC664
Edit7: added AmpereOne
Edit8: added Cortex-X4, Cortex-A720 and Cortex-A520
Edit9: added TaiShan v120

[ Edited by Andreas_Wolf 13.12.2023 - 00:08 ]