Lindwyrms are serpent like creatures similar to that of a wyvern. They are long snake like creatures with wings and feet but unlike dragons have no arms. They appear frequently in Norse myths and sagas. The name Lindwyrm comes from the old norse word Linnormr or ‘Ensnaring snake,’ and also go by the names Ormr or snake and Dreki or dragon. Some believe these creatures have fire breath or poisonous breath like Fafnir others argue this point.
In the Norse Sagas 9 are specifically mentioned although there could be others, Odin himself refers to these lindwyrms as Ormr, these are
Nidhoggr (Malice Striker) lives in an area in the wastes of Niflhel where the very worst souls linger in the area known as Nastrond or “The Corpse Shores,” where he eats the corpses of the honour less dead such as Oath breakers and Murderers. Whilst there he chews on the roots of Yggdrasil.
Fafnir “In the Icelandic Volsunga Saga (late 13th century), Fáfnir is a dwarf with a powerful arm and fearless soul. He guards his father's house of glittering gold and flashing gems. He is the strongest and most aggressive of the three brothers.Regin recounts to Sigurd how Odin, Loki and Hœnir were traveling when they came across Ótr, who had the likeness of an otter during the day. Loki killed the otter with a stone and the three Æsir skinned their catch. The gods came to Hreidmar's dwelling that evening and were pleased to show off the otter's skin. Hreidmar and his remaining two sons then seized the gods and held them captive while Loki was made to gather the ransom, which was to stuff the otter's skin with gold and cover its outside with red gold. Loki fulfilled the task by gathering the cursed gold of Andvari as well as the ring, Andvaranaut, both of which were told to Loki as items that would bring about the death of whoever possessed them. Fáfnir then killed Hreidmar to get all the gold for himself. He became very ill-natured and greedy, so he went out into the wilderness to keep his fortune, eventually turning into a serpent or dragon(symbol of greed) to guard his treasure. Fáfnir also breathed poison into the land around him so no one would go near him and his treasure, wreaking terror in the hearts of the people. Regin plotted revenge so that he could get the treasure and sent his foster-son Sigurd to kill the dragon. Regin instructed Sigurd to dig a pit in which he could lie in wait under the trail Fáfnir used to get to a stream and there plunge his sword, Gram, into Fafnir's heart as he crawls over the pit to the water. Regin then ran away in fear, leaving Sigurd to the task. As Sigurd dug, Odin appeared in the form of an old man with a long beard, advising the warrior to dig more trenches for the blood of Fafnir to run into, presumably so that Sigurd does not drown in the blood. The earth quaked and the ground nearby shook as Fafnir appeared, blowing poison into his path as he made his way to the stream. Sigurd, undaunted, stabbed Fafnir in the left shoulder as he crawled over the ditch he was lying in and succeeded in mortally wounding the dragon. As the creature lies there dying, he speaks to Sigurd and asks for his name, his parentage and who sent him on such a dangerous mission. Fafnir figures out that his own brother, Regin, plotted this, and predicts that Regin will also cause Sigurd's death. Sigurd tells Fafnir that he will go back to the dragon's lair and take all his treasure. Fafnir warns Sigurd that all who possess the gold will be fated to die, but Sigurd replies that all men must one day die anyway, and it is the dream of many men to be wealthy until that dying day, so he will take the gold without fear.”- Wikipedia extract
Jormungandr (Huge Serpent) is also called the Midgardr Serpent and is the child of Loki and Angrboda. He is is so huge he circles the oceans surrounding Midgardr and is the fated slayer of Thor his greatest enemy at Ragnarok.
“When they came to him, straightway he cast the serpent into the deep sea, where he lies about all the land; and this serpent grew so greatly that he lies in the midst of the ocean encompassing all the land, and bites upon his own tail.”- Prose Edda.
Grabakr (Greyback), Grafvolludr (Grave Burrower), Ofnir (The Entangler), Svafnir (Sleep inducer), Grafvitni (Grave Wolf), Goinn (Deep within Earth) and Moinn (Moor Beast) are all Dark spotted Wyrms living beneath the tree Yggdrasil and gnawing at its roots.
There may well be more in the legends and sagas, but its clear that these creatures are evil and enemies of the nine realms.