The Black Watch, 3rd Battalion, is an infantry battalion of the Royal Regiment of Scotland.

Prior to 28 March 2006, the Black Watch was an infantry regiment in its own right; The Black Watch (Royal Highland Regiment) from 1931 to 2006, and The Black Watch (Royal Highlanders) from 1881 to 1931. Part of the Scottish Division, it was the senior regiment of Highlanders.

The regiment's name allegedly came from the dark tartan that they wore and from its role to "watch" the Highlands. "Black Watch" was originally a nickname for the 42nd (Royal Highland) Regiment of Foot, but was used more
and more so that, in 1881, when the 42nd amalgamated with the 73rd Regiment of Foot, the new regiment was named "The Black Watch (Royal Highlanders)". The uniform changed over time, but the nickname has been more enduring. The regiment adopted the royal motto of Scotland's Stewart monarchs, Nemo me impune lacessit (no-one provokes me with impunity).