"House of M" is a Marvel Comics storyline that centers around the character Wanda Maximoff, also known as the Scarlet Witch. After experiencing immense grief over the loss of her children, Wanda uses her reality-altering powers to create an alternate universe where mutants are the dominant species, and her father, Magneto, rules as a king. This new reality drastically changes the lives of many characters, including Spider-Man and Wolverine. The storyline explores themes of power, loss, and identity, as characters grapple with their new roles in this altered world. Eventually, the consequences of Wanda's actions lead to significant events in the Marvel Universe, including the decimation of mutantkind, which is a pivotal moment in the X-Men series.