A four funnel liner, four funneled liner or four stacker is an ocean liner with four funnels. The SS Great Eastern, launched on the 31st of January 1858 became the first and only ocean liner to ever sport five funnels, as one funnel was later removed the Great Eastern also by de facto become the first ocean liner to sport four funnels. The SS Kaiser Wilhelm der Grosse, christened May 4 1897, was the next ocean liner to sport four funnels and was one of the first of the golden era of ocean liners that become prominent in the early 20th century. . Perhaps the best known four funnel liners are the RMS Titanic which sunk after striking an iceberg on her maiden voyage and the RMS Lusitania which was torpedoed during World War One.
In all, fifteen four funnel liners were ever built, the Great Eastern in 1858 and the remaining fourteen all between 1897 and 1922. Four of these sunk during World War I, and apart from the Titanic, the remaining were scrapped. RMS Mauretania was the fastest of all four funnel liners. The last four funnel liner ever built was the SS Windsor Castle but her two funnels were removed (either SS Arundel Castle and SS Deutschland), making RMS Aquitania the last four funnel liner in service, which she the only one to survive both World Wars and the biggest of all four funnel liners.