Languages other than English also use trigraphs.
Some languages use trigraphs to represent their native triphthongs when using plain Latin alphabet without diacritics.
See Digraph (orthography) for more explanations.
Longer "multigraphs" are also known. It is quite possible that the lognest one is a "heptagraph" schtchj used in German language to represent a Russian palatalized phoneme щь (which is, by the way, represented by a digraph in Russian language).