But Cox, the black, transgender actress who plays Sophia Burset on the show, said she thinks Hough acted out of ignorance, not malice or racism.
"I wasn't offended," Cox told UsMagazine.com. "I thought it was a shame that she is in this country, that she would wear black-face and not understand the historical implications of that. I don't think Julianne is making a specific informed choice to comment on blackness. I just think it's out of this ignorance. That's really sad."
Cox went on to say Hough was "obviously a fan of our show. I love Crazy Eyes, too."
Hough tweeted an apology shortly after photos of her costume were posted online and ignited a media firestorm.
"I am a huge fan of the show Orange is the New Black, actress Uzo Aduba, and the character she has created," Hough wrote.
"It certainly was never my intention to be disrespectful or demeaning to anyone in any way. I realize my costume hurt and offended people and I truly apologize."