In theory, pretty much any thread can be used for longarm quilting. We're only listing those who market their products as specifically being made for quilting. Otherwise this list would be to long to keep up with or be useful to those looking only for thread made for quilting.
You may notice that some threads are listed as Top Thread or Bobbin Thread. This is noted because that's how the manufacturer regards these threads on their website. If there is no designation, either we missed it or the manufacturer feels it is suitable for both purposes. Generally speaking though, any thread listed as a Top Thread can be used in the bobbin. It's just a matter of getting your tension set correctly.
Below you will find longarm quilting thread manufacturers and their respective social media presence. Please let us know of any other manufacturers or brands not listed here or if any get discontinued and should be removed.
Note: Not all of the Manufacturers sell directly from their website. Sometimes the links will be more informational than retail. Even if you find it online for sale, please ask your local quilt shop if they carry the brand; it's important to support them. Supporting your local quilt shop supports the manufacturer as well!