Many thousand exoplanets candidates have been identified, 3671 of which have been confirmed (as of Oct 2017). In the Milky Way galaxy, it is expected that there are many billions of planets (at least one planet, on average, orbiting around each star, resulting in 100–400 billion exoplanets, with many more free-floating planetary-mass bodies orbiting the galaxy directly. The nearest known exoplanet is Alpha Centauri Bb.
Almost all of the planets detected so far are within the Milky Way; however, there have been a small number of possible detections of extragalactic planets.
Some known exoplanet systems from Astronomy Magazine, Feb 2015.