The name of the Norse tree that connects the nine worlds is Yggdrasil. This immense and central cosmic tree represents the structure of the universe and is an integral part of Norse cosmology. It connects various realms, such as Midgard (Earth), Asgard (home of the gods), and Hel (the underworld). Yggdrasil is also associated with various creatures that reside among its branches and roots, symbolizing the interconnectivity of all life.