Euclid: Discovery of 31 new quasars at 6.6< 7.8

We report the discovery of 31 new high-z quasars in the redshift range 6.6 &lt; z &lt; 7.8. These quasars were selected from approximately 3000 deg(2) of sky covered during the first 1.5 years of the EuclidWide Survey, representing the initial results of the Euclid high-z quasar search. Our candidate selection employed multiple machine-learning and probabilistic techniques applied to the Euclid I-E, Y-E, J(E), and H-E images, supplemented by ancillary z-band data when available. Spectroscopic follow-up observations were carried out with Keck, Magellan, and the Large Binocular Telescope (LBT). Among the new discoveries, there are 12 quasars at z &gt;= 7, more than doubling the number of previously known quasars at z &gt;= 7. The newly discovered quasars exhibit 21.2 &lt; J(E) &lt; 23.2 ( 25.5 &lt; M-1450 &lt; -23.6), extending quasar studies to the faint end of the quasar luminosity function (QLF) at z greater than or similar to 7. The quasar with the highest-z, EUCL J172902.75 + 641018.1 at z approximate to 7.77, sets the new redshift record for the most distant quasar ever reported. These discoveries demonstrate Euclid's transformative role in high-z quasar discovery and set the stage for future follow-up studies of the early galaxies hosting quasars, supermassive black hole growth, and the intergalactic medium in the epoch of reionisation.