[=SS501=] (usually pronounced "double S five o' one") [[KoreanPopMusic Korean boyband]] debuted on June 8, 2005 with their first single, "Warning". The five members are:
* Kim Hyun Joong, the {{Cloud Cuckoo Lander}} leader. Nicknamed "Leader" to differ himself and the maknae whose names are similiar.
* Heo Young Saeng, quiet and cares a lot about his image.
* Kim Kyu Jong, the kind, obedient one.
* Park Jung Min, the most talkative member.
* Kim Hyung Joon, the baby in both age and personality. Nicknamed "Baby" to differ himself and the leader whose names are similiar.

They started in their late teens and have gained decent popularity. However they've been inactive as a whole group since 2010, with everyone pursuing solo activities and joining other companies, and performed as a whole group once in 2013. It's been stated that they have not and will not disband.

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!!Tropes associated with [=SS501=]:
* TheBandMinusTheFace: As [=SS501=] Special Project Group, the group promoted with 3 members in 2008 while Kim Hyun-joong was busy filming ''Series/BoysBeforeFlowers''. Park Jung-min was also participating in the musical ''Theatre/{{Grease}}''. The project group later became official in their own right in 2016 as Double S 301.
* BoyBand: Obvious KoreanPopMusic example.
* CloudCuckoolander: Hyunjoong, oh so much. He had talked to a dog before, and he had also posted a fanfiction along with insane drawings that he had made himself.
* NiceGuy: Kyujong. He's very obedient and kind to the other members. For example, he sacrificed himself to be the violent waker Jungmin's roommate when they go on a beach trip to see the sunrise. He's also the one who turns off the lights for the lazy Hyunjoong when Jungmin, who had came in the room, only scolds the leader for being lazy.
* ScreamsLikeALittleGirl: Jungmin does this a lot.
%%* TeamDad: Hyunjoong can be this.
%%* TeamMom: Jungmin, according to the fans.
* TrademarkFavoriteFood: Seasoned roasted chicken for Youngsaeng and carrots for Jungmin. The latter even has a rubber carrot toy (he claims that it's a cucumber, though).
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