De kan inte dö av ålder, men de kan dö av svärdet eller sorgen.
Enligt Tolkien, när en Elf blir en vuxen, slutar de bli äldre. De är också mindre utsatta mot fysisk skada, men de är inte odödliga. Elvernas liv uthåller sig bara när världen håller på att gälla.
Elvar kan dödas eller dö av sorg (deras ande lämnar sin kropp), men de är inte utsatta för ålder eller sjukdom.
När en Elf dör, går hans ande till Mandos för sin dom, och efter en väntetid kan han återkomma.
Enligt Wikipedia
Elves are naturally immortal, and remain unwearied with age. In
addition to their immortality, Elves can recover from wounds which
would normally kill a mortal Man. However, Elves can be slain, or die
of grief and weariness.
Spirits of dead Elves go to the Halls of Mandos in Valinor. After a
certain period of time and rest that serves as "cleansing", their
spirits are clothed in bodies identical to their old ones.
However, they almost never go back to Middle-earth and remain in
Valinor instead. An exception was Glorfindel in The Lord of the Rings;
as shown in later books, Tolkien decided he was a "reborn" hero from
The Silmarillion rather than an individual with the same name. A rare
and more unusual example of an Elf coming back from the Halls of
Mandos is found in the tale of Beren and Lúthien, as Lúthien was the
other Elf to be sent back to Middle-earth – as a mortal, however.
Tolkien's Elvish words for "spirit" and "body" were fëa (plural fëar)
and hröa (plural hröar) respectively.
Intressant info från här
While the three cycles are not specifically defined, the first cycle
is likely childhood and adolescence, which ended at the 100th year,
the second is adulthood which could continue for Ages, and the third
is for extremely old Elves;
Elves did not physically age after they reached maturity, but they did
age in a different sense than Men. They became ever more weary of the
world and burdened by its sorrows.
Elves are naturally immortal; like the Ainur, they are bound to Arda
until its End. Elves are immune to all diseases, and they can recover
from wounds which would normally kill a mortal Man.
De enda "odödliga varelserna" i LOTR är soldaterna för The Dead of the Dead. Dödsarmén förbjöds av Isildur med odödlighet i form av en existens som odöda skelett efter att de övergav sin ed i Kriget om den sista alliansen. Deras enda chans att dö var att uppfylla sin eder .