In House M.D., what is the name of the private investigator hired by Gregory House?

Lucas Douglas is the private investigator hired by Gregory House in House M.D.

House employs Lucas during the sixth season to investigate people and gather information that House cannot easily obtain through ordinary medical or hospital channels. Lucas is unconventional, observant, and comfortable operating outside formal professional structures.

Michael Weston played Lucas Douglas. The character becomes more than an investigator: he develops a friendship with House and a romantic relationship with Lisa Cuddy. That connection places Lucas directly inside the show's central personal and professional conflicts.

Lucas is sometimes confused with Michael Tritter, the detective who investigates House after a confrontation in a clinic. Tritter is an antagonist connected to a legal storyline, whereas Lucas is the private investigator House personally hires.