Player was an examine which appeared by right clicking near the Customs Sergeant's boots. On 19 May 2009 the player was removed from the game during a patch. The patch note quotes "Removed an invisible character who didn't do anything".
Other invisible NPCs can be seen at various resting spots, including some at Varrock, Draynor Village, and Shantay Pass, on nearby Music appreciators' heads. These invisible NPCs have the examine text "I am invisible!" but cannot be talked to or attacked and have very small clickboxes. It is likely that these NPCs exist to give the Customs Sergeant and appreciators, which are not actually NPCs, a yellow dot on the minimap, to make them look like NPCs.