The King's Own Scottish Borderers (KOSBs) was a line infantry regiment of the British Army, part of the Scottish Division. On 28 March 2006 the regiment was amalgamated with the Royal Scots, the Royal Highland Fusiliers (Princess Margaret's Own Glasgow and Ayrshire Regiment), the Black Watch (Royal Highland Regiment), the Highlanders (Seaforth, Gordons and Camerons), the Argyll and Sutherland Highlanders (Princess Louise's), 52nd Lowland Regiment, and 51st Highland Regiment to form the Royal Regiment of Scotland, becoming the 2nd Battalion of the new regiment. However, after just a few months the battalion merged with the Royal Scots (1st Battalion) to form the Royal Scots Borderers. In 2021, the battalion was disbanded and its personnel transferred to the 1st Battalion, Ranger Regiment.