The key question here is: what is the definition of the goldilocks zone? Assuming the key is to maintain liquid water on a planet's surface, then there are many different parameters:
1. The amount of energy hitting the planet from stars
2. The thickness and composition of the planet's atmosphere
3. Other characteristics of the planet (mass, composition of solids, presence/absence of geological cycles, internal heat sources, etc.)
There is also the possibility of maintaining liquid water somewhere other than a planet's surface. For instance, several Solar System bodies are thought to have long-lived subsurface oceans: Europa, Ganymede, and Ceres are the most promising.
The phrase "goldilocks zone" makes the assumption that the only relevant quantity is the orbital distance to one or more stars. But there is no need to be so restrictive.
Here are a few examples of situations that answer the question:
1. A super-Europa with a rocky core and an ocean covered with a few miles-thick ice layer. Assuming an Earth-like abundance of lon-lived radionuclides such as Uranium, the ice layer acts as a thermal blanket to maintain the ocean in a liquid state. This planet can be free-floating in the galaxy, as it has no need for an external heat source.
2. An Earth with a thick hydrogen atmosphere (10-100 bars works). In this case the hydrogen atmosphere acts as the thermal blanket that maintains liquid water on the planet's surface.
These two worlds are not "Earth-like" but they do maintain liquid water. With these two worlds there is no "goldilocks zone" of required orbits, there is just a zone that is disallowed too close to any stars. 188
Basically, it can't get too hot.
FYI, see these two links for details about worlds 1 and 2: http://aeon.co/magazine/science/can-life-exist-on-a-planet-without-a-star/ https://planetplanet.net/2015/06/04/real-life-sci-fi-world-8-the-free-floating-earth/
1. A Jupiter-mass black hole orbits a Sun-like star in the classical habitable zone, with an Earth-like "moon" orbiting the black hole.
2. Earth orbiting a brown dwarf. Brown dwarfs don't burn hydrogen so they simply cool off in time. However, there is a set of orbits for which there is a billion-year window of goldilocks conditions (see here: https://planetplanet.net/2014/10/09/real-life-sci-fi-world-4-earth-around-a-brown-dwarf/)
3. A planet in the habitable zone of a white dwarf. I suppose it's semantics whether a white dwarf counts as a star or not.
4. It's a bit more speculative, but how about a planet that is free-floating within a star cluster that receives a pulse of energy every time it flies by some bright stars, then spends the next 10,000 years cooling off slowly. Whether this is viable would depend on the nature of the planet's atmosphere, how close it flies to what types of stars, etc. But not impossible.
To re-iterate my key point, the whole concept of the goldilocks zone is very limited. Earth itself -- with its current properties -- has at least 4 possible stable climates (see here: https://planetplanet.net/2016/04/06/no-livable-planets-without-life/). We are lucky to be in the goldilocks climate. 24