In Greek mythology, Alseids (/ælˈsiːɪdz/; Ancient Greek: Ἀλσηΐδες, romanized: Alsēḯdes) were nymphs who inhabited groves.^[1]

They are mentioned by Apollonius of Rhodes,^[2] who relates that the woman Cleite hangs herself after the death of her husband, Cyzicus, who was killed by the hero Jason.^[3] Upon her suicide:^[4]

Even the woodland nymphs themselves lamented her death, and from all the tears they shed for her from their eyes to the ground, the goddesses made a spring, which they call Cleite, the famous name of the unfortunate bride.

A scholium on the Iliad (from the A family of scholia)^[5] states explicitly that "Alseids" is the name given to nymphs who occupy groves.^[6]

• Apollonius Rhodius, Argonautica, edited and translated by William H. Race, Loeb Classical Library No. 1, Cambridge, Massachusetts, Harvard University Press, 2009. ISBN 978-0-674-99630-4. Harvard University Press.
• Dindorf, Karl Wilhelm, Scholia Graeca in Homeri Iliadem, Volume II, Oxford, E. Typographeo Clarendoniano, 1875. Internet Archive. Perseus Digital Library.
• Erbse, Hartmut, Scholia Graeca in Homeri Iliadem (Scholia vetera): Volumen V Scholia ad libros Y - Ω continens, Berlin, De Gruyter, 1977. ISBN 9783110069112. doi:10.1515/9783110850222.
• Grimal, Pierre, The Dictionary of Classical Mythology, Malden, Oxford, and Carlton, Blackwell Publishing, 1986. ISBN 0631201025. Internet Archive.
• Larson, Jennifer, Greek Nymphs: Myth, Cult, Lore, Oxford University Press, 2001. ISBN 978-0-19-512294-7.
• Oxford Classical Dictionary, edited by Simon Hornblower and Antony Spawforth, Oxford and New York, Oxford University Press, 2003. ISBN 0198606419. Internet Archive.