Scotland Yard

"Working together for a safer London"

—Official motto

The Metropolitan Police Service (MPS), the police force of most of Greater London (the tiny City of London has its own, separate police force despite being only a Square Mile). Metropolitan is from Metropolis, meaning "Capital City".

The HQ of the Met is at New Scotland Yard, just opposite St. James' Park tube station. This is actually the second New Scotland Yard. The force is divided into borough commands, each having a two letter code seen on officer's shoulder numbers.

The Met Police is one of the two UK forces led by a Commissioner as opposed to a Chief Constable. This is currently Sir Bernard Hogan-Howe.

In fiction

In the nineteenth and early twentieth centuries, when few police forces outside London had trained detectives, they would often call on Scotland Yard to send one to investigate any serious crime whose perpetrator wasn't obvious or where a suspect was socially important enough to make arresting them embarassing for a local cop (the real-world source of the Smith of the Yard trope). This is very rare now in Real Life unless you were dealing with a wandering Serial Killer and even then, real-life local forces would object. However, it often appears in works with contemporary settings by American authors whose knowledge of British police procedure still comes mostly from Agatha Christie or Dorothy L. Sayers novels.

Rules for inclusion here:

They must be the stars.
The force must be identified as the MPS on screen or in dialogue.

Examples of Scotland Yard include:

Literature

The Alleyn novels of Ngaio Marsh.
The Daisy Dalrymple novels by Carola Dunn. Daisy persists in tripping over bodies and almost invariably ends up calling in Cheif Inspector Fletcher of the Yard. This is made easier later in the series after they marry.

Live Action TV

Ashes to Ashes
Between the Lines is about the Metropolitan Police's Internal Affairs, at the time known as the Complaints Investigation Bureau (it's now the Directorate of Professional Standards).
The Bill
The Inspector Alleyn Mysteries
The Inspector Lynley Mysteries
Luther
New Tricks
Waking the Dead