1. Girl's Day
Girl's Day are known for being reverse-idols after their transformation from debut to their comeback (member changes aside). However, that wasn't the most surprising thing to happen - it was when they went from concepts from "Twinkle Twinkle" to "Something" that wowed every fan!
While the boys have dramatic transformations altogether, member Ren wowed everyone the most when he went from a more feminine image to a strong, gentleman like concept alongside the boy group.
3. Hello Venus
Hello Venus dropped the cute act after "Would You Like Some Tea" and stepped their game up with "Wiggle Wiggle." Pop lock and drop it, ladies.
The boys of B1A4 were always cuties but they surprised all of K-Pop when they came back with their Western cowboy theme in comparison to their past concepts.
5. Fat Cat
Fat Cat debuted with a badass concept with "My Love Bad Boy" and became a sweet, mature women with tracks like "It's A Dream."
6. Boys Republic
Boys Republic were getting the party started with "Party Rock" until they become moody, sensitive boys in "Hello."
Only once did 4minute try to switch up their trendy, pop girl concept to become an adorable band in "What A Girl Wants." It was a hit and miss for some.
GOT7 became every girl's best friend with "Just Right" but suddenly switched things up with their darker style in "If You Do."
"If you wanna pretty, everyone a pretty," remember this cute line? Everyone couldn't forget but fans were left with their jaws on the ground once they picked things up with their sexy concept "Lupin."
10. Co-ed School
Although the group only made two tracks, each one was completely different. Their debut track was more fun and colorful where as "It's Too Late" was strong with intense choreography and a rough construction style.
Everyone couldn't stop talking about CLC's "Hobgoblin" come back! The girls were dark, fierce and sexy in comparison to their fun and funky style in "No Oh No."
The boys of 100% are known for switching between concepts like nothing. The boys impressed many with their darker tracks such as "Beat" and then sweet and charming tracks such as "U Beauty."
13. Dal Shabet
Dal Shabet wowed us all when they become attention-grabbing chic women in their model like MV for "B.B.B." Looking back on cutesy tracks like "Pink Rocket" and "Supa Dupa Diva," this switch was completely unexpected.
The veteran group SHINee have mastered many concepts over the years, but their most notable one was their complete 90s transformation in "1 of 1."
Last but not least, the girl group Stellar were the queens of switching up concepts. After having a hard time gaining attention with previous styles like in "Rocket Girl" and "UFO," the whole K-Pop scene was shook when they dropped the sex bomb in "Marionette."