WIPO has a patent search interface that covers PCT applications and many national databases, including Europe, Japan, Korea, Russia, many Latin American countries, and more. I think all currently-applicable patents in these countries are covered, and there is additional historical data for some countries, but some of them only index metadata and abstracts, only a few provide full-text search.
EPO has a patent search interface, Espacenet which includes a search engine for European and PCT patents and applications as well as links to other countries' databases (especially Asian countries).