To my bias for the longest time (since 2008-2009), Choi Minho, from a boy to a man now. He announced on mid-March that he will be enlisting in the marine cops in April
Minho wrote his last letter to Shawols before enlisting: “time has flown by so quickly since the debut on May 25 in 2008. They were all happy, joyful, and unforgettable moments, because we shared such wonderful memories together”, “I will consider this as a period to reflect upon myself and the past”, “I will miss you all so much. I feel so bad for having been unable to approach you guys easily to express my feelings!”, “I will never let you down.”

On 15 April, Minho officially enlisted at the Marine Corps training center. Apart from the other two members that are already in the military. Close friends of Minho from SM Entertainment went to send him off.

Let’s listen to the last and probably the only solo song from Minho while waiting for his safe return in 2 years time.
Source: (1)
Timeline – SHINee members enlistment
10 December 2018 – Onew’s enlistment
4 March 2019 – Key’s enlistment
15 April 2019 – Minho’s enlistment