Billie Eilish celebrated her 21st birthday with a star ... a limited edition Twenty One T-Shirt on her store to mark the occasion, which reads "been a good girl for 21 years" on the front.

Sydney Thomas celebrated her milestone 21st birthday ... In her birthday post, Thomas showcased her Vegas style, donning a black dress, a floral top, and a sheer long-sleeve shirt paired with ...

Kendall Jenner recreating Paris Hilton’s 21st birthday look on her own 21st birthday ... Scott backstage while wearing a Von Dutch t-shirt and pink Juicy Couture sweatpants with her flip phone ...