I am planning on logging into my unix desktop via an Anroid tablet. Is there a terminal emulator that will allow me to view images, such as making plots in ipython, via X11 protocol?
Technically, you can run an X server on Android.
For a bare X11 server, see Play store: X Server for example.
That could help with very special needs, like showing a plot window on fixed screen position with no window manager for example.
You could run a full xsession on that display of course, but I think that is not too useful in most general cases.
You would use a normal terminal emulator, and set the display to your X server. (You could run a terminal emulator like
xterm on the X server of course - but the X11 keyboard simulation will not really be useable.)