The term Illion or Ilium has several meanings, including in legends, in anatomy, and in the arts:

• Ilion or Ilium is an alternative name (in Greek and Latin, respectively) for the legendary city of Troy.
• Ilio, or Ilion or Nea Liossia is a suburb of Athens, Greece.
• The ilium, or ilion (not to be confused with the ileum), is a bone, part of the pelvis.
• Ilium is also the name of an Australian power metal band.
• Ilium is also the name of a post-rock instrumental band.
• Ilium is the name of a novel by Dan Simmons published in 2003.
• Ilion, New York is a village in Herkimer County, New York.
• Ilium is a fictional town in upper New York state, used as a setting for many of Kurt Vonnegut's novels.
• Ilium is a bone in the pelvis.