New Zealand & Australia

De Linum - linen linen linen
https://www.delinum.com.au/
looks like online only?: NSW Australia

Fibresmith - natural fiber and yarn
https://fibresmith.com.au/
3/10 Akuna Drive
Williamstown North
VIC (Appointments for warehouse shopping)

Beautiful Silks - silks and environmentally sustainable textiles. Lots of great supplies for natural dyeing.
https://www.beautifulsilks.com/
Looks like online post covid: VIC Australia

We Are the Fabric Store: they have everything  https://wearethefabricstore.com/  Multiple locations Based in New Zealand & Australia

Draper's Fabrics: High quality dress fabrics  https://drapersfabrics.com/ 
Auckland, New Zealand

Hawes & Freer: Fine Fabrics & Supplies (I love their bridal fabric section)
https://www.hawesandfreer.co.nz/ 
Auckland, New Zealand

Miss Maude: Fine Fabric & Yarn  https://missmaudesewing.co.nz/ 
Greytown, Wairarapa, New Zealand

UK

VV Rouleaux: Fine ribbons bits & bobs  https://www.vvrouleaux.com/ 
London, UK

Merchant & Mills: fine fabrics -linen, wool, cotton, sustainable options, oilcloth  https://merchantandmills.com/ 
Rye, East Sussex UK

Bawn Textiles: Specifically focused on sustainable and organic fabrics and notions  https://bawntextiles.com/ 
Glasgow Scotland, UK

Europe:

Pretty Mercerie: apparel fabrics & more
https://prettymercerie.com/
Manou, France
I can’t tell if they are online only

Canada
-starting from the east:

Fiver Arrows Fabrics: small but mighty apparel fabrics  https://fivearrowspei.ca/  Charlottetown, Prince Edward Island, Canada

Patch Halifax: a little bit of everything  https://www.patchhalifax.com/ 
Halifax, Nova Scotia, Canada

Fabrications Ontario: a little bit of everything plus knitting supplies  https://fabricationsottawa.com/ 
Ottawa, Ontario Canada

Needlework: a little bit of everything + felting, embroidery etc.  https://www.iloveneedlework.com/ 
Hamilton, Ontario Canada

L'oiseau Fabrics: a little bit of everything  https://www.loiseaufabrics.com/ 
Calgary, Alberta Canada

Blackbird Fabrics: wool, linen, cotton, hemp, some deadstock rayon/modal/tencel/bamboo  https://www.blackbirdfabrics.com 
Online only based in Vancouver, British Columbia Canada

USA
-starting from the east:

Fiddlehead Artisan Supply: cotton, linen, wool, silk, rayon, errythang  https://fiddleheadartisansupply.com/ 
Belfast, Maine USA

Zele Nava: Linen, multiple weights  https://zelenava.net/ 
Waltham, Massachusetts USA

Grayline linen: mostly imported linen, some silk & cotton blends -be careful of weights as they carry multiple weights for upholstery etc.  https://www.graylinelinen.com/  
New York, NY USA

Burnley & Trowbridge: "Purveyors of accurate goods for historical fashion"  https://burnleyandtrowbridge.com/ 
online only based in Williamsburg, Virginia USA

Treadle Yard Goods: a small but lovely supply of apparel and quilting cotton  https://www.treadleyardgoods.com/ 
Saint Paul, Minnesota USA

Lakes Makerie: a smattering of lovely apparel fabrics and notions  https://lakesmakerie.com/  Minneapolis, Minnesota USA

Fancy Tiger Crafts Co-op: a little bit of everything including deadstock fabric & yarn supplies too  https://fancytigercrafts.com/  Denver, Colorado USA

Material Goods: a focus in thoughtfully curated materials, notions, & supplies for modern makers
Online only, based in Denver https://www.materialgoods.us/

Elfriede’s Fine Fabric: beautiful everything
https://www.elfriedesfinefabrics.com/
Boulder, Colarado

Stone Mountain & Daughter: a little bit (lots actually) of errrythang  https://stonemountainfabric.com 
Berkley, California USA

Lyrical Fabrics: focusing on deadstock & sustainable fabrics  https://lyricalfabrics.com/  online only based out of San Francisco, CA USA (can be found on etsy as well)

Renaissance Fabrics: Fine historical fabrics and notions  https://renaissancefabrics.net/  Clayton, California USA

This one is huge and is in San Francisco:
Britex Fabric: Everything  https://www.britexfabrics.com/ 
San Francisco, California USA

These two are also huge, like fabric district huge in NYC:

B & J fabrics: Everything  https://www.bandjfabrics.com/ 
New York, NY USA

Mood Fabrics: Everything  https://www.moodfabrics.com/ 
New York, NY USA

& in my home state: North Carolina, USA Mulberry Silk Fine Fabrics -they don't really have an online shop BUT if you live in the southeast region of the US you can call them and ask for samples if you are after a certain something & their shop is lovely  https://mulberrysilks.net/ 
Carrboro, North Carolina USA

Japan

Miss Matatabi: many types of apparel fabrics
https://shop.missmatatabi.com/
Kanagawa, Japan