A G-line in Internet Relay Chat refers to a global network ban applied to a user.

G-line may also refer to: G (New York City Subway service) G Line (Los Angeles Metro), a bus rapid transit line in Los Angeles County, California G (Los Angeles Railway), former streetcar service G Line (RTD), commuter rail line serving Denver, Colorado Goubau line, a single-wire transmission line or waveguide The peak at 435.8 nm on the emission spectrum of mercury. See . Metro G Line (Minnesota), a planned bus rapid transit line in Minneapolis–Saint Paul, Minnesota G (SEPTA Metro), a trolley Line in Philadelphia.