Lynel of Ploymus Mountain
The mountain was the territory of a Lynel since before the Great Calamity as one terroried Zora's Domain in the past according to two weathered Zora Stone Monuments and Mipha's Diary only to be defeated by the Knight and Hero Chosen by the Master Sword Link. Mipha's Diary reveals the full story of how Princess Mipha told Link of the Lynel causing him to travel to Ploymus Mountain to slay the beast. Mipha secretly followed Link who upon discovering her told her to return to Zora's Domain but she stubbornly refused. Suddenly the Lynel attacked them though Link easily defeated it with his sword skills, finishing it off with a Spin Attack. Link was hailed as a hero for defeating it and the Zora Helm was placed in a small shrine at Toto Lake in rememberence.
One hundred years later, Link finds a Lynel living on the mountain (it is unclear if the one Link defeated previously was resurrected by Calamity Ganon or if it is a descendant of the Lynel that Link slayed in the past). Like the Lynel in the Coliseum Ruins, this Lynel is not replaced by stronger Lynels as Link progresses through the game and is resurrected after every Blood Moon. During the Side Quest "Lynel Safari", Laflat asks Link to take a picture of this Lynel with the Camera Rune and will reward him with the Zora Greaves after showing it to her.