300 million light-years
This group of five is really a group of four, with the fifth coincidentally in the line of sight. The spiral galaxy at the upper right of centre is about eight times closer to us than the other four, something not discovered until 1961. The rest of the galaxies show signs of complex interaction and seem to be on a collision course.
Credit: Image made in visible light by T. Rector (U. Alaska Anchorage) for the Gemini North Observatory.