A few unusual artists I love are:
Rainbowdragoneyes: Metal/Chiptune fusion.
Mili: A Japanese Indie group with Pop, Classical, Electronic influences. They did the Opening theme for Goblin Slayer. They also did an awesome cover of Still Alive. Their biggest appeal is definitely Momo’s vocals.
Utsu-P: HEAVY METAL VOCALOID. (yes really)
I will be quite surprised if anyone else is listening to Mylla, a swedish band where their first album is very “flower power” inspired, and their second album is more rooted in 60s rock…
Mylla - Kobran (from their first album, Vanja) : https://www.youtube.com/watch?v=rYl0vRkeOI8
Jack stauber
this is a fan music video that got me into him https://www.youtube.com/watch?v=eYDI8b5Nn5s
here is the album he uploaded to youtube https://www.youtube.com/watch?v=40R49TvD_FM
Unknown Mortal Orchestra: https://www.youtube.com/watch?v=IJrKlSkxRHA
mother mother: their style is more rock oriented but I ts rather unique I find https://www.youtube.com/watch?v=4o0WYiK52Dg
Here is a few norwegian oddities :
Katzenjammer - Hey ho (on the devils back) : https://www.youtube.com/watch?v=tDK5sSwcBtM
Katzenjammer full concert : https://www.youtube.com/watch?v=_bwE4pjcISU
Kaizers Orchestra - resistansen : https://www.youtube.com/watch?v=utMixwWWOaA
Kaizers Orchestra - Mann mot mann : https://www.youtube.com/watch?v=0meo0G0UXjY
Both bands are a bit of acquired taste i guess, but both bands have had some success outside of Norway, although i guess most will not have heard about them 
I’m not sure how unusual they may be, but I think Diablo Swing Orchestra is pretty unique. Each of their albums has a slightly different style. An example from the latest album: https://www.youtube.com/watch?v=H2SR15Atlww
I’m guessing your from Norway? I really like some of Katzenjammer’s stuff. “A bar in Amsterdam” probably being my favorite.
marcgii:
yeah, im from Norway, and i guess i would not have a clue about those bands if i where not. Katzenjammer and Kaizers Orchestra is far from the typical Norwegian pop tunes though, and that is probably why i like them so much
John 5, for whatever reason… 0_o
I’ve seen plenty of instrumental metal vids on Youtube. This one stand outs from the rest, XD
I got a few hidden gems
As a guy that is particularly interested in unique and unusual artists/songs I might have a few of interest.
Andreas Vollenweider’s album ‘Down to the Moon’ is fantastic and one of my go to relaxation albums.
Jacob 2-2 is a pretty cool dude
Sevish is one a few microtonal artists that I like a lot.
Could never find to much info on Cujo but the song is sick.
The Dresden Dolls are pretty interesting. Love their sound.
Jeremy Dutcher - Wolastoqiyik Lintuwakonawa
Reincarnation of songs from the Wolastoqiyik Nation generations ago. All the songs were on wax cylinders originally.
Listening through Ola Kvernberg - Steamdome right now. Saw them live last november where they performed the album (and then some) live. The concert lasted 2 hours or so, and guys on drums/rhythm really had a workout
You can listen to steamdome on Spotify, and their other albums, although i think steamdome is where they are at their best, but youre mileage may vary
First 2 songs performed live here: https://www.youtube.com/watch?v=S45cJ-Tc7vA
Also, would recommend a listen to “The low frequency in stereo”, especially their debut album with the same name. Its rather lo-fi progrock but they has quite a few strong melodies. They are a local band, so i’ve seen them a few times live and they always put on a good show.
If it’s about “unique” the first thing that comes to mind is the Canadian duo Elsiane (Elsieanne Caplette + Stephane Sotto) and their fusion of electronica, jazz and symphonic:
Currently lots of black ambient and ritualistic music. Typically lots of reggae and dub, classic punk, 80’s & 90’s alt, some metal and a touch of jazz.
I worship The Jesus and Mary Chain, The Cramps, Clash, Bad Brains and Sonic Youth.
These are current obsessions:
Trepaneringsritualen
MZ.412
Vril Jäger
Heilung
Osi and Jupiter
Kollaps
HIDE
Khruangbin
They don’t like to categorize their music into existing genres, but from existing reviews the description is something like: Thai funk inspired surf soul / psychedelic rock. Mostly instrumental, but they did cautiously add a few lyrics here and there (none are trained vocalists).
They have a new album announced for July on their Bandcamp: http://khruangbin.bandcamp.com
The Comet is Coming; self-described “Apocalyptic Space Funk,” aka 3 dudes from Brooklyn and one brought a sax.
Here’s something you don’t hear every day: the jazz-instrumental reframing by Jan Garbarek of some medieval Norwegian songs performed by Agnes Buen Garnås on vocals:
A couple of tracks are so out there I can’t really make myself listen to them, but most are good, and a couple are so good I could’ve easily seen them used as intros for trailers or episodes of “Vikings”, e.g.:
I like what I’m hearing. Going through their discography now. 