Suggestions by @cocona

Idris Elba

as Severus Snape in Harry Potter (all black cast)

Morgan Freeman

as Albus Dumbledore in Harry Potter (all black cast)

Leon Thomas III

as Ron Weasley in Harry Potter (all black cast)

Jaden Smith

as Harry Potter in Harry Potter (all black cast)

Zendaya Coleman

as Hermione Granger in Harry Potter (all black cast)

U-KNOW Yunho

as Arthur Weasley in Harry Potter kpop

Kwon BoA

as Molly Weasley in Harry Potter kpop

Choi Siwon

as Horace Slughorn in Harry Potter kpop

Jessica Jung

as Dolores Umbridge in Harry Potter kpop

Sandara Park

as Sibila Trelawney in Harry Potter kpop

Hwang Chan-seong

as Alastor Moody in Harry Potter kpop

Danielle

as Lily Luna Potter in Harry Potter kpop

Lee Jun-ho

as Bill Weasley in Harry Potter kpop

Jonghyun

as Albus Dumbledore in Harry Potter kpop

Baekhyun

as George Weasley in Harry Potter kpop

Krystal Jung

as Narcissa Malfoy in Harry Potter kpop

Krystal Jung

as Narcissa Malfoy in Harry Potter kpop

Jisoo (Kim Ji-soo)

as Cho Chang in Harry Potter kpop

Mingyu

as Cedric Diggory in Harry Potter kpop

Shin Dong-yup

as Petter Pettigrew in Harry Potter kpop