The Whitetrees are a crime family in Boston.

"First daughter" and presumptive heir Chelsea Whitetree, better known as Elsie Blackwood (the E in MMFEC), fled to Seattle with her mentor and self-styled British butler, Magnusson Cromwell.

Chelsea's alias and new life in the shadows didn't prevent her family to catch up to her and nearly succeed in having her kidnapped (episodes 23 to 25).