Largest extroplanet

In terms of physical size, the largest extrasolar planet discovered to date is HD 100546 b which has been estimated to be 965,000 km across.

Discovered in 2005, this planet candidate is large enough to be very close to the boundary between giant planets and brown dwarf stars, and may turn out not to be a planet at all.

It orbits the star HD 100546, also known as KR Muscae, in the constellation Musca approximately 320 light years away. The star itself is about 10 million years old and is surrounded by a disk of material and appears to be forming a new planet.