Lagan may refer to:
- Places
- River Lagan, river in Northern Ireland
- Laganside Corporation, public body formed to regenerate the Lagan in Belfast
- Lagan College, the first integrated school in Northern Ireland
- Lagan Valley, valley in Northern Ireland
- Lagan Valley (Assembly constituency)
- Lagan Valley (Northern Ireland Parliament constituency)
- Lagan Valley (UK Parliament constituency)
- Lagan, County Armagh, townland in County Armagh, Northern Ireland
- Lagan (river), river in south-western Sweden
- Lagan (locality), locality in Ljungby Municipality, Sweden, named after the river
- Lagan, Russia, town in the Republic of Kalmykia, Russia
- Media
- Lagaan, 2001 award-winning Bollywood movie
- "Lagan", a song by the Afro Celt Sound System from the album Volume 3: Further in Time
- Lagann, a mech in the Gurren Lagann anime
Lagan may also mean:
- goods abandoned at sea but secured to a buoy; see Flotsam and jetsam