Alpha Centauri was an inhabited planet in the Alpha Centauri system.
In an alternate timeline, created by Jonathan Archer being infected by interspatial parasites, the Xindi destroyed Earth in 2154 and then proceeded to annihilate all other Human settlements, including Mars, Alpha Centauri, and Vega colony. (ENT: "Twilight")
In the mid-23rd century, in a cafe on this planet, the romance between Paul Stamets and Hugh Culber began. (DIS: "Magic to Make the Sanest Man Go Mad")
In 2338, Greta Vanderweg was born on this planet. (DS9: "Field of Fire")