The Württemberg Tssd was a class of German 0-4-4-0T narrow gauge, steam locomotive operated by the Royal Württemberg State Railways.

They were initially deployed on the Öchsle Railway in 1899 between Biberach an der Riß and Ochsenhausen.

A total of nine units were delivered in three series of three engines in 1899, 1901 and 1904 with fleet numbers 41–49.

T is the abbreviation for tank locomotive, ss means that it is a narrow gauge locomotive with a rail gauge of 750 mm (2 ft 5+1⁄2 in), and the letter d, added later, was the abbreviation for duplex locomotive, because the steam was expanded twice, first in the high-pressure cylinders and then in the low-pressure cylinders.

Locomotive 99 633 was under the ownership of the German Railway History Company (DGEG) and was loaned to the Öchsle Schmalspurbahn (Öchsle Narrow-Gauge Railway) and displayed in the Ochsenhausen shed, its original home.