Mrs. Nyxly is the landlord in the apartment building where Clark Kent first lived when he moved to Metropolis, and one of the few who first learned he was Superman and kept it a secret. Unbeknownst to him, she was also the wife of Mister Mxyzptlk, who was hiding in Metropolis from her husband's jealous rival Vyndktvx, after he killed her father in the Fifth Dimension. While he eventually found and killed her on Earth, she escaped death and returned to the Fifth Dimension with her husband by hiding in the second dimension, in the Red of Superman's "S" symbol.