Dobby (real name Debbie) is Mark's post-Sophie love interest. She is an IT technician at JLB Credit until the entire office staff are laid off. In many ways she is similar to Mark in that she is an outsider - a girl who likes video games and fantasy roleplaying. However, she is more outgoing than Mark and her desire for adventure puts a strain on their relationship at times. She is also quirky, as evidenced by her style of clothing and use of "personal cheese" in the lunchroom when she and Mark first meet.
Although their relationship is waylaid by various awkward situations and Mark's primary love rival Gerard (with whom Mark forms the Dobby club), by the end of series 7 Dobby has agreed to move in with him. Throughout series 8, a variety of events seem to conspire to keep Dobby from moving in to Mark's flat. After a disastrous weekend in the Quantocks during which Mark brings Jeremy along, she accepts a job offer and heads to New York with her ex-boyfriend Simon.