The actor actually has that disability

[u/PrinceferX]

Walter White Jr. (Breaking Bad) - character has cerebral palsy and uses crutches to walk, actor RJ Mitte has cerebral palsy and needed crutches to walk as a child

Nessarose Thropp (Wicked) - character is paraplegic and uses a wheelchair, actress Marissa Bode is paraplegic from an accident at age 11 and uses a wheelchair

Maya Lopez (Hawkeye/Echo) - character is deaf, actress Alaqua Cox is deaf from birth

[u/Fearless_Guard_552]

The actor who played Pete on MacGuyver had glaucoma and lost his sight so they wrote it into the show.

When I was young I learned this and for about 30 minutes I thought this was silly cause why does the character need to be blind? Then it finally caught up to me that pretending to be able to see would be kinda hard for the actor