The Trossachs (; Na Tròiseachan) generally refers to an area of wooded glens, braes, and lochs lying to the east of Ben Lomond in the Stirling council area of Scotland. The name is taken from that of a small woodland glen that lies at the centre of the area, but is now generally applied to the wider region.
The wooded hills and lochs of the area may be considered to represent a microcosm of a typical highland landscape, and the woodlands are an important habitat for many species. Much of the Trossachs area is protected by various different conservation designations, including the Great Trossachs Forest National Nature Reserve.
The Trossachs form part of the Loch Lomond and The Trossachs National Park, which was established in 2002. The area has long been visited by tourists due to the relative proximity of major population centres such as Glasgow and Stirling, and remains popular with walkers, cyclists and tourists. Scenic boat rides on Loch Katrine are popular with visitors: the steamer SS Sir Walter Scott, launched in 1899, remains in operation. The Great Trossachs Path, one of Scotland's Great Trails, is a 48 km route suitable for walkers, cyclists and horse riders. It runs between Callander in the east and Inversnaid on the banks of Loch Lomond in the west, passing along the northern shores of Loch Katrine and Loch Arklet.
The name Trossachs involves the Brittonic root trōs meaning "across" (c.f. Welsh traws), perhaps conserving the compound trawsfynydd meaning "cross-hill".
Also suggested is a derivation from a Gaelic word for "bristly".
The Trossachs glen lies between Ben A'an to the north and Ben Venue to the south, with Loch Katrine to the west and Loch Achray to the east. It lies at the centre of the wider region, which is generally regarded as being bounded by Glen Gyle to the south, with the western boundary being the road between Stronachlachar and Aberfoyle. Loch Doine, Loch Voil, and Loch Lubnaig form the northern and eastern boundary of the area.