There are at least five bands named Ethos:
1) A symphonic rock band from Fort Wayne, Indiana, USA, that was formed in 1973:
Here is an excellent example of the US Progressive rock scene of the Seventies: having both technique and excellence, imagination & talent. They seemed to be influenced by a variety of styles. Their sound was a little folky at times, poppy at others, even a little jazzy at times, loosely in the shadow of KANSAS, YES, GENESIS, early KING CRIMSON and others, with lots of vocals everywhere.

The eponymous album was recorded in 1975, "Ardour" the following year, while "Relics" is a compilation of tracks originally destined for the band's third album. The album "Ardour" is excellent. Cool cover too.
www.progarchives.com

2) A progressive rock band from Georgia, USA, that formed in 2009. Ethos is known for blending the raw energy of rock and metal with the sophistication of classically inspired motifs and captivates audiences with their innovative fusion of heavy riffs, intricate piano melodies, and soul-stirring vocals.

3) A thrash metal band from Logroño, Spain.

4) A Progressive rock band from Romania, active in the late seventies and early eighties:
http://www.discogs.com/artist/Ethos+%287%29

5) A Hip hop supergroup, consist of K-Otix and other Houston-based rappers.
http://www.discogs.com/artist/3630342-Ethos-9 Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.