Are there any galaxies that are partially with the visible universe? It seems unlikely as most of the universe is empty space however our circumference makes it seem likely as well. It would be a rather interesting thing to know about.
Perhaps, on rare occasions this will occur. Quoting from Phil Plait in an astronomycast ,
Dr. Plait: Yeah, because the universe is expanding ever faster every day, basically the distance we will be able to see, away from the earth, is going to get closer and closer to us. Anything past the distance will be moving away from us too rapidly to see and so eventually, all that is going to be left is some sort of super galaxy that is us and the Andromeda galaxy and all of the little dwarf galaxy’s, will have all combined into, sort of, one thing. Of course, all of the stars will be dead and then that’s it.
So, you know, if you are a civilization, somehow, that evolves a hundred trillion years from now, the universe is going to look way different than it does now. You are not going to see any other galaxies; it’s just going to be you.
Frazier: You are not going to see any stars, because it will all be dark.
Dr. Plait: That’s right and for a long period of time that is all there is going to be, it’s just going to be that. Even on the scale of what we are talking about, we are talking about a long period of time, now instead of an octillion years, which is what, ten to the twenty seven, now we are starting to talk about ten to the fifty and sixty years, so far into the future, that the present age of the universe, 13 billion years, is so small, that I don’t even have, ten to the sixty divided by ten to the thirteen is ten to the forty seven, that is such a huge number, that there is no ratio that exists today.
On those expansion scales, a galaxy is small (!!) enough that it'll pretty much disappear all at once.
The observable universe, by definition, is the area of the universe from which light has reached us.
While this boundary could lie in the middle of a galaxy, some of the oldest light (at the edge of the observable universe) could be old enough that it originates from a time before galactic formation. In this case, the cutoff could exist on a semi-congealed mass of gas or whatever structure was present at the time, but there would be no galaxies to speak of.