User:SOTO/Forum Archive/The Reference Desk/@comment-7657843-20161112133450/@comment-1432718-20161112145615
From Tardis Wiki, the free Doctor Who reference
The answer depends on what you consider a spin-off. Are you interested in the prose, audio, comic, etc spin-offs? If so, there are quite a few.
Someone will correct me if I'm wrong, but I believe you covered all the TV spin-offs.