Q. Is it correct for children to wear on Purim a costume that resembles King Achasverosh or Haman, who were evil people?
A. See question 3064 above regarding the sources and reasons for wearing attires and disguises on Purim.
Horav Shlomo Miller’s Shlit’a opinion is that it is better to avoid costumes. that have any negative connotation, as they may affect a child’s emotions and spiritual health.
Rabbi A, Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit”a