The Finn is a shadowy, strange character who appears in Neuromancer, Count Zero and Mona Lisa Overdrive. The Finn wears a battered tweed jacket, smokes Partegas, and is fond of pickled herring. He has a set of large, backwards-pointing yellow teeth, tiny ears and a head that seems to be built for aerodynamics. He makes his home in a dilapidated building in the Sprawl, which seems to be held up by walls, piles and towers of junk. At the core of the accreted garbage is the Finn's inner sanctum - a spotlessly white clean room, protected by walls of electronic jamming circuitry.

The Finn's business is somewhat unclear (or rather, undefined), but it is undoubtably shady. In Neuromancer Molly pays him to scan Case for bugs and harmful devices. He also helps identify the AI, Wintermute. However, his usual business seems to be as a fence for stolen software, or more rarely actual physical items. The Finn is a close acquaintance of Molly Millions.

Some time between Count Zero and Mona Lisa Overdrive, the Finn seems to have been killed, or at least ceased to exist in a biological form. His mind lives on as software, a personality construct housed in an armoured shell bolted to the pavement in a dark dusty back alley filled with junk in the heart of the Sprawl. Seeing with laser light and talking through a loudspeaker, the personality construct doubles as the local oracle. In front of the shell that houses his construct lie gifts - alcohol, cigarettes, voodoo symbols in flour (or occasionally cocaine) - none of which he can touch. He seems to be reasonably satisfied.