5. Izuna Uchiha
Izuna Uchiha was the younger brother of Madara Uchiha. He was a couple of years younger than Madara Uchiha. Since, Madara Uchiha awakened his Sharingan at about 17 as said earlier, meaning Izuna Uchiha must have awakened his Mangekyou Sharingan at around 15 years.
4. Kakashi Hatake
Kakashi Hatake received the Sharingan as a gift from Obito Uchiha, when Obito was crushed under a huge boulder. Since then, Kakashi Hatake started using the Sharingan. He awakened the Mangekyou Sharingan when his friend Rin killed herself with Kakashi’s Chidori blade. He was around 14 years old at this time. He, like Obito, had Kamui Mangekyou Sharingan allowing him to send things into different dimension.