The Highland Railway K class were the only class of 0-6-0 tender locomotives built for the Highland Railway. They were introduced in 1900, to the design of Peter Drummond. The class were known as 'Barneys'.

They were fairly standard for British practice of the time, inside cylinders with 5 ft 0 in (1.524 m) diameter driving wheels and a general Drummond family appearance.

The first six (nos. 134 to 139) were built by Dübs and Company in 1900. These had inside bearing double bogie tenders, rather like the watercart designs brother Dugald was supplying on the London and South Western Railway. These were later transferred to C and U class (Ben) locomotives.

Four more (nos. 18 to 21) were supplied by Dübs in 1902. These omitted the watercart tenders but had another Drummond family speciality – cross water tubes in the firebox. No 21 is recorded as retaining this boiler in unmodified form until 1934.

A final pair (nos. 36 and 55) were built by the North British Locomotive Company in 1907.

All passed into London Midland and Scottish Railway (LMS) ownership in 1923. The first was withdrawn in 1936.

Seven survived into British Railways (BR) ownership in 1948. The last was withdrawn in 1952.