Colossus Telescope

The Colossus Telescope (cited with The, i.e., "The Colossus Telescope") is a concept for a future telescope larger than the European Extremely Large Telescope (E-ELT). The concept features an effective primary mirror aperture of 50 meters using 60 individual 8-meter mirrors. (Being at the concept stage, somewhat different numbers have been cited.) It differs from segmented-mirror designs in that each 8-meter mirror would have a dedicated 18-mm secondary mirror and optical interferometry would be used to produce the output image, though each primary mirror would be off-axis, aiming light at a tightly-packed group of secondaries. Due to gaps between the individual mirrors, and an overall hexagonal shape, the collecting area would be about 70% of that of a single 50-meter mirror.

The PLANETS telescope (for Polarized Light from Atmospheres of Nearby Extraterrestrial Systems) is a 1.85-meter telescope in development for Haleakala Observatory, Maui, Hawaii, which is to double as a pilot for some of Colossus's technology. The ExoLife Finder (ELF) is a proposed telescope, essentially a scaled-down version of the Colossus, with sixteen 5 meter primary mirrors and a 25-meter diameter (with the potential for high angular resolution but limited collecting area). I'm guessing this scaled-down version still did not attract enough interest to make much progress.