SM Rookies

SM Rookies (, stylized as SMROOKIES) were a pre-debut training team created by South Korean entertainment agency SM Entertainment in 2013. It comprised young trainees who have yet to debut in an idol group. On the course of its program, the team has produced and promoted idol groups such as Red Velvet and NCT.
History.
2013–17: Formation, debuts of Red Velvet and NCT.
SM Entertainment formally announced the formation of SM Rookies on December 3, 2013, featuring members Seulgi, Jeno and Taeyong. On December 9, Irene, Jaehyun and Lami were introduced. On December 16, the members Mark, Hansol and Jisung were introduced, followed by Johnny, Ten and Yuta on the 23rd.
Wendy was introduced on March 13, 2014, with the song "Because Of You" for the soundtrack of the SM C&C-produced series "Mimi". On March 19, 2014, a video of Wendy singing the song “Speak Now” by Taylor Swift was released. In April, SM launched the official website of the project. The agency announced the opening with a video teaser uploaded onto SM's official YouTube channel. On July 16, a dance performance video of Irene and Seulgi dancing to the song "Be Natural" by S.E.S. was released under the name SR14G. Donghyuck was later introduced on July 17, 2014. On July 21, Taeyong released a track video for the song “Open The Door”. On July 22, Mark and Donghyuck were featured in the first video of the "Rookie Station".
Later that month, the agency confirmed Irene, Wendy and Seulgi as members of the group Red Velvet. On August 14, trainee Yeri was featured in the third video of the "Rookie Station" alongside Taeyong, Yuta, Jaehyun, Mark, Jeno and Donghyuck. On the 21st, they released the fourth video of the "Rookies Station" series. On August 24, a video of Johnny, Taeyong and Hansol dancing to the song "Super Moon" under the name of SR14B was released. On September 16, 2014, the sixth video of the "Rookie Station" was released, featuring members Johnny, Yuta, Ten and Jaehyun. 
On October 9, 2014, Taeyong was featured in Red Velvet’s single “Be Natural”.
On January 16, 2015, Doyoung was introduced as he and Jaehyun were to become the new MCs on MBC Music's "Show Champion". In February, a report about Red Velvet filming a music video with trainee Yeri was leaked online. The following month, SM Entertainment formally introduced Yeri and was announced to debut as the fifth member of Red Velvet immediately. On March 6, 2015, a clip of Hansol, Johnny, Taeyong, Yuta, Ten and Jaehyun dancing to the song “Bassbot” under the name of SR15B was released. After months of being featured in various SM Rookies events, Jaemin was formally introduced in April 2015. On July 8, 2015, Koeun, Hina and Herin were introduced as they were to become "mouseketeers" on Disney Channel Korea’s "" alongside Mark, Jeno, Donghyuck, Jaemin, Jisung and Lami. On July 26, SM Entertainment announced a concert for the male members titled "SM Rookies Show".
On July 30, a video of Hansol, Johnny, Taeyong, Yuta, Ten and Jaehyun performing a dance routine, under the name of SR15B was released. On October 13, 2015, Taeil was introduced after being featured in SM Rookies events. In November 2015, The SM Rookies Girls performed a dance in a video "ROOKIES ENTERTAINMENT APP LAUNCHING". On December 18, 2015, Kun was formally introduced. Later on December 22, 2015, Lami, Hina and fellow trainee Park Jungyeon made an appearance in the "Winter Garden 2015" promotional video teasers.
On January 5, 2016, WinWin was introduced. SM Entertainment founder Lee Soo-man announced a concept for a new boy group, that would be debuting with different teams based in different countries around the world. On January 26, Taeil released the song “Because Of You” for the soundtrack of the series "". In April 2016, the agency announced Taeil, Taeyong, Doyoung, Ten, Jaehyun and Mark as members of NCT's first subgroup, NCT U. In July 2016, it also confirmed Yuta, WinWin and Donghyuck (now officially known as Haechan) as members of NCT's second subunit, NCT 127. In August 2016, the agency confirmed Jeno, Jaemin and Jisung as members of NCT's third subgroup, NCT Dream, alongside Mark and Haechan.
On September 19, 2016, Yiyang and Ningning were introduced to the public followed by their appearance on the online reality show "My SMT". In December 2016, the agency confirmed Johnny as a new member of NCT's Seoul-based unit, NCT 127.
On April 5, 2017, Lucas was introduced, followed by Jungwoo on April 17. Jungwoo and Koeun made an appearance in the music video of Super Junior member Yesung's single "Paper Umbrella" later that month. Kun made his re-appearance in the team alongside Lucas and Jungwoo after almost a year of absence, opening the pre-debut team's Instagram account.
On late June 2017, Herin was confirmed as a contestant of Mnet's survival show, "Idol School", leading to her departure from the pre-debut team and SM Entertainment. Hansol followed suit in October and participated as a contestant in the upcoming KBS survival show "".
2018: New NCT members, WayV's debut, members departure, and culmination of the project.
In January 2018, NCT unveiled a "large scale project" for the year called 'NCT 2018' and some members were seen in Ukraine filming a music video for a possible comeback. SM Rookies members Jungwoo and Lucas were spotted alongside the other NCT members in the airport en route to the said country. 
On January 30, SM Entertainment confirmed the upcoming debut of the remaining SM Rookies members Kun, Lucas, and Jungwoo through the video NCT 2018 Yearbook #1. On February 13, it was revealed that Lucas and Jungwoo would be making their official debut through NCT U's comeback single "Boss" alongside members Taeyong, Doyoung, Jaehyun, Winwin, and Mark. The music video for "Boss" was released on February 18.
On July 17, 2018, three male Chinese trainees, Hendery, Xiaojun, and Yangyang, were introduced. On October 1, 2018, it was confirmed that Yiyang (이양) has left SM Entertainment and returned to China to join the idol competition show "The Next Top Bang".
On December 31, 2018, SM Entertainment announced the debut of Hendery, Xiaojun and Yangyang as members of the NCT's Chinese sub-unit, WayV. After the debut of WayV, the project was informally halted.
2020: Member departures and formation of Aespa.
In February 2020, it was reported that Koeun and Lami had left SM Entertainment, which was later confirmed with the removal of their names from Korean portal sites on February 24. Hina was also confirmed to have left SM Entertainment on October 15, 2020 after opening her personal Instagram account.
On October 26, 2020, SM announced the formation of new girl group, Aespa (æspa), which debuted on November 17, 2020. On October 29, SM Entertainment confirmed that Ningning will be a part of the girl group and was re-introduced as the group's third member.
Among the team's thirty official members, twenty-four of them have made their official debut while the remaining six have left SM Entertainment, thus putting an end to the pre-debut team.
Discography.
Songs recorded.
Names in "italics" indicate other participated trainees at the time of the event.
Concerts.
Concert participation.
Names in "italics" indicate other participated trainees at the time of the event.