Where is an EASA PPL valid outside of Europe?
Yes, the EASA PPL is valid worldwide, but you must check the local laws prior to fly, for example, here in Brazil to fly a Brazilian registrated airplane (PT-***) you shoud have an ANAC PPL license, but if you are flying to Brazil in an UK based Aircraft( reg. G-****), you can fly it with your EASA PPL.

If you intent to Fly a Non-European aircraft for a long period in a same country, you should validate your EASA license within the local Aviation Authority, that ensures that you get the same level of license as you have from EASA.