The Colossus Telescope (cited with The, i.e., "The Colossus Telescope") is a concept or a future telescope larger than the European Extremely Large Telescope. The concept features an effective primary mirror aperture of 50 meters using 60 individual 8 m mirrors. (Being at the concept stage, somewhat different numbers have been cited.) It differs from segmented-mirror designs in that each 8 m mirror would have a dedicated secondary mirror and optical interferometry would be used to produce the output, 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 50m mirror.
The PLANETS telescope (for Polarized Light from Atmospheres of Nearby Extraterrestrial Systems) is a 1.85 m telescope in development for Haleakala, Maui, Hawaii, which is to double as a pilot for some of Colossus's technology.