hugedomains, as mentioned above for being one of the worst, do this. They own their own registrar/are part of the same company / some convoluted ownership structure (namecheap LLC I think)?
This is the thread where someone mentions they /had/ their domain with namecheap, which is why I confused them: https://www.namepros.com/threads/held-hostage-by-huge-domain...
Personally I've never used either - I'm in the UK so it is different companies (oneandone are who I've used, who have been fine)