| Äio | |
| Type: | Studio |
| Artist: | Metsatöll |
| Cover: | Metsatöll - Äio.jpg |
| Released: | March 3, 2010 |
| Recorded: | August–September 2009 |
| Genre: | Folk metal, heavy metal |
| Length: | 59:44 |
| Label: | Spinefarm |
| Producer: | Metsatoll |
| Prev Title: | Iivakivi |
| Prev Year: | 2008 |
| Next Title: | Ulg |
| Next Year: | 2011 |
Äio is a release from Estonian folk metal band Metsatöll, released worldwide in 2010 on Spinefarm Records. It features heavy use of traditional instruments such as the Estonian: italic=no|lokulaud, Estonian: italic=no|[[torupill]], Estonian: italic=no|[[Kannel (instrument)|kannel]], and Estonian: italic=no|angipill, in addition to the typical metal band instrumentation (electric guitars, bass, drums, etc.)
In the May 2010 issue of Terrorizer magazine, writer James Hoare spoke with vocalist/piper Lauri "Varulven". Lauri is quoted as saying "No other countries have such good researchers of traditional culture and folklore than among oppressed peoples." Hoare also went on to praise the release, giving special note to the choir; the Estonian National Male Choir participated on the track "Ema hääl kutsub".