The Great Tree is a location in Tangled: The Series. It is a massive, hollow tree that used to be Zhan Tiri's stronghold when she corrupted it with dark magic. Lord Demanitus rendered it dormant by throwing an enchanted spear into its heart.
Eons ago, the Great Tree was once a sentient being and a force for good. However, at some point it was corrupted by the evil demon Zhan Tiri, who made the tree her stronghold and used it to destroy any who approached it. Ultimately, Zhan Tiri's reign over the Great Tree came to end when Lord Demanitus threw a magic spear into the heart of the tree, rendering it's corrupted magic dormant and forcing Zhan Tiri to abandon it.
Thousands of years later, Hector, a dangerous member of the Brotherhood, was sworn to remain at the Greet Tree as his domain to ensure no one could through it to reach The Dark Kingdom.