Halloween is portrayed as a gothic-looking girl, with long black hair and a crucifix necklace.  She and two other holidays, Christmas and Guy Fawkes Day, left Holiday Island to form a band. Halloween claims that one of the reasons she found the place intolerable is because she had to be happy all the time.

At first, Halloween doesn't think Daria is cool, but after Daria buys pizza for everyone she changes her mind.

Since she is absent from Holiday Island, the sales of Halloween candy drop noticeably. While staying at the Morgendorffer home, she somehow inspires cobwebs to grow on the walls, and organizes mischievous outings with unknown co-conspirators on the phone.

She sparks a heated battle between herself and her fellow Holiday runaways when she gets a job and refuses to share her paycheck with them. The battle is interrupted when Daria announces she has found them a paying gig - back at Holiday Island.