In the world of triple offset butterfly's - aside from Vanessa as already mentioned, the other "Big Ones" in manufacturing are Tomoe-Tritech ( South Wales in the UK, .. and Headquartered in Japan ), Solent & Pratt, who used to be a nice independent UK company and have now been swallowed up by the bigger Curtiss-Wright group, and Orton SpA, based in Piacenza in Italy, and who are part of the FCx Group of companies.
The Far-East / Pacific Rim recent 'explosion' of manufacturer's have yet to really get their heads around TOBV's, both in 'design' and especially when it comes to 'exotics' in material spec's, but rest-assured, they WILL get there, and probably very quickly.
When it comes to double-offset and standard 'rubber lined' butterfly's.. the world is literally one's oyster ... there are a multitude of companies manufacturing and distributing - it all comes down to the old adage, " Ye pay for what ye get, my son "
Its easy to get a hold of really cheap and cheerful equipment ( as it is in virtually every sphere of valves ) but some of them wouldn't hold back snow, never mind any form of pressure containment.
To summarise - its horses for courses.. consider your application and the media to which you wish to subject the valve to, with a thought being given to all the usual temperature / pressure / chemical resistance criteria, and select something thats "fit for purpose"
Cheers.
VG