An alphabetic listing of all the pen makers’ sites I can find, large and small. No endorsements here, as I’ve not tried many of them– they’re here because they exist and they make fountain pens. Note that there are some which exist but have no website; they will not be mentioned here. For an item that “no one uses anymore,” there’s a surprising number of manufacturers.
Bic (they do, despite appearances in the North American market, make fountain pens under their own name)
Camlin (makers of Camel ink)
Sailor (but there is also a US and a UK site us English speakers can enjoy)
Skriss (They now have an English language side, but sometimes it wanders back into Turkish)