The word "troll," like its concept, came into the English-speaking world in 1859 with a translation of Norwegian oral tradition. This included the story of "Three Billy Goats Gruff, which featured a troll under a bridge, introducing that motif into the popular English-speaking lexicon. The following excerpt may help; coming from my book Trolls: From Scandinavia to Dam Dolls, Tolkien, and Harry Potter, which draws on the 1936 dissertation by Elisabeth Hartmann (1912-2004) , Die Trollvorstellungen in den Sagen und Märchen der Skandinavischen Volker. She was a student of Sven Liljeblad (1899-2000) and Carl Wilhelm von Sydow in the tradition of Jacob Grimm.

I was Sven's last student, under whose direction I read/translated Hartmann's dissertation. And then I corresponded extensively with Hartmann during the last five years of her life, so I was able to discuss my project with her. I added sections on the diffusion of the various forms of Scandinavian trolls into the English-speaking world. Your question focuses specifically on the Norwegian species.

Here is the excerpt:

Trolls became a permanent fixture in English literature during the nineteenth-century craze for international folklore. The great Norwegian collectors Peter Christen Asbjørnsen (1812-1885) and Jørgen Engebretsen Moe (1813-1882) published the first of many editions of Norske Folkeeventyr – Norwegian Folktales in 1841, giving literary life to the remarkable realm of Scandinavian folklore, and to its trolls. When Sir George Webbe Dasent (1817-1896) released his translation of their work in 1859, he provided English-speakers with access to that world.

Dasent’s Popular Tales from the Norse made “troll” a household English word. The all-time favorite, “The Three Billy-Goats Gruff,” became particularly important. This simple story introduced English readers to “a great ugly troll, with eyes as big as saucers, and a nose as long as a poker” who lived under a bridge. The folktale features three goats, each larger then the next and each named Gruff. One at a time, the goats attempt to cross the bridge that serves as shelter for the troll. The monster threatens to eat the first, who tells him not to bother but rather to wait for the next who would serve as a much better meal. The second Billy-Goat Gruff says the same thing. Finally, the third goat arrives. It is so large it can kill the troll and eliminate the threat once and for all.

The troll in “The Three Billy-Goats Gruff” is typical of his Norwegian brethren. Together with trolls in other stories, these monsters introduced themselves to Britain and North America. Initially imported by Dasent’s translations, the newly arrived troll assumed a singular, hideous, malevolent image detached from the complexity of its homeland folklore. In its expansive homeland, the Scandinavian word “troll” assumes a wide variety of forms representing diverse beliefs and stories. Trolls can be everything from grotesque fiends with exaggerated features and a hatred of people to alluring, dangerous individuals more akin to Celtic fairies. It all depends on where they are found.

While I can't add to /u/itsallfolklore's great discussion of how 'troll' entered English language (and imagination), I would suggest that the more general idea of monsters living at watery edge-spaces (like bridges) can be traced back in English as far as Beowulf (Grendel and his mother, called ettins - giants / monsters - in the poem, live in a swamp, on the edge of Hrothgar's land).

Swamps, water, and places where they're crossed play an important, if poorly understood, role in English ritual practice (starting in prehistory, and continuing through the late middle ages). There's a great article, published in the edited volume, The Cross Goes North, which traces ritual activity at a causeway that crossed a swamp. Weapons were thrown into the water along the causeway, from the Bronze Age through the late middle ages, with few interruptions - the waterway, and the causeway that crossed it, was a place where boundaries broke down and these kinds of rituals had to be performed, for a really really long time.

You see other evidence of the importance and danger - in a very longue duree sense - of water courses, swamps, and bridges in English archaeological and written sources. For example, Guthlac retreats to a swamp to hide from the world (in the Vita Guthlaci, an 8th century text), and is attacked by demons. A man buried in the sixth century was nailed to the ground - perhaps because they were afraid he would try to come back - in the edges of a swamp.

None of these things are trolls hiding under a bridge, but you can make a strong anthropological argument that these more recent stories of trolls at water crossings are tapping into a much older uneasiness about crossing water.