Most Important Early Releases of Technical and Progressive Thrash Metal
This list tries to reveal who invented technical and progressive thrash metal - I'm starting with the most important releases. I focused on the time order and not on the quality of the songs, EPs and albums but you can vote for what you like.Technical and Progressive Thrash Metal emerged in the early to mid-80s. The first releases were demos on cassettes with bad sound quality but I actually enjoyed listening to them - the joy of the discovery.
Some of these first songs were re-recorded later and released on albums many metal fans know.
A demo with 4 songs released in 1984. The song Meltdown doesn't have much thrash in it but the other 3 songs have some progressive and technical thrash feel to them. To me this demo sounds more like prog metal with thrash elements. Songs:
1. Meltdown
2. Tyrants in Distress
3. Argonne Forest
4. Cimmerian Shadows
Watchtower was a massive inspiration for other metal bands to start adding progressive elements to their music. They definitely deserve to be at the top of the list.
This demo contains songs that were included in Annihilator's debut album, released 4 years later (1989): Human Insecticide, Welcome to Your Death, Crystal Ann, Burns like a Buzzsaw Blade. Human Insecticide appears on the demo with a different title (Lust of Death).
This is already true thrash with technical and progressive elements.
Songs:
1. Crystal Ann (instrumental)
2. Welcome to Your Death
3. Lust of Death (this is Human Insecticide, they changed the title)
4. Burns like a Buzzsaw Blade
5. Back to the Crypt
6. I Am in Command (they put it on their 2nd album - Never, Neverland /1990)

Album released and recorded in 1985.
"Energetic Disassembly is notable for its heavy use of time changes and is considered to be a landmark in progressive metal." (wiki)
Coroner sound was influenced by Rush in the progressive/technical part. Coroner were originally roadies for Celtic Frost and on this demo vocals were provided by the Celtic Frost singer Tom G. Warrior.
This song sounds like Aces High by Iron Maiden meets YYZ by Rush. Singer imitates either Geddy Lee (but he's better) or Bruce Dickinson (most often). Drumming is thrashy from time to time.
However, to me this song is more prog metal than prog thrash but I believe the idea of mixing metal with Rush prog sound and technicality was important.
Look at the songs on this demo - Annihilator fans know them because they were on Annihilator's first 2 albums released 3-4 years later (1989, 1990):
1. Gallery
2. Alison Hell
3. Phantasmagoria
4. Ligeia
Hellwitch released a song earlier (Nosferatu, 1984) - I gave it a listen because I expected to be a thrash song for this list but guess what: it's death metal! (with some small technical and progressive elements). Who knew there were death metal songs before Possessed...

It's Coroner's debut album. I love it - songs are great. I wish mixing was better though.
The album featured bass player Ron Broder on vocals and he assumed the role for the rest of the band's existence.


Probably my favorite Coroner album.

A true masterpiece.
D.T.P. = Death To Posers (the correct demo title is D.T.P. and not D.T.R. I made a mistake, sorry.)
It's about 30 minutes long. I liked it very much. I even found a remastered version on YT.
A 10 minute long demo with 2 songs - Hands of Fate, Number One (instrumental).
I liked Hands of Fate. But Coroner instrumentals are much better.