RMS Teutonic was an ocean liner built for the White Star Line in Belfast, which entered service in 1889.

Teutonic and her sister were the flagships of White Star Line's fleet for around a decade, until Oceanic entered service in 1899.

Teutonic was historically notable for three reasons; for being the first armed merchant cruiser, for being the inspiration behind Germany's Kaiser-class ocean liners, and for being the last White Star ship to hold the Blue Riband.

The ship was completed on 25 July 1889 and participated in the Spithead Naval Review on 5 and 6 August, in conjunction with the state visit of Kaiser Wilhelm II.

[3] Although Queen Victoria remained aboard the royal yacht, the Kaiser was given a two-hour tour of the new ship hosted by the Prince of Wales, the future Edward VII.

In August 1891, Teutonic won the Blue Riband from her sister Majestic, with a timing of 5 days, 16 hours and 31 minutes between Queenstown and Sandy Hook, with an average speed of 20.35 knots (37.69 km/h; 23.42 mph), she would hold the title for one year before losing it to City of Paris.

In 1898, she had a minor collision in New York Harbor with the United States Lines' Berlin, but neither ship suffered major damage.

[1] In 1907 Teutonic, along with Majestic, Oceanic and the new Adriatic was transferred to White Star's new 'Express Service' between Southampton and New York via Cherbourg and Queenstown.

She was transferred to White Star's sister company Dominion Line for a Canadian service, which ran from Liverpool, and terminated at Montreal in the summer season, and Portland, Maine in the winter.

"[7] In August 1914, with the start of World War I, Teutonic was requisitioned by the Royal Navy for use as an Armed Merchant Cruiser which she had been designed for.

She was commissioned into the 10th Cruiser Squadron, where she took up position on the Northern Patrol between the Faroe Islands and the ice belt, and in the Denmark Strait between Iceland and Greenland.