There are multiple artists under the name.

Cincinnati, Ohio, United States (2016 - present)
Marr is a female-fronted shoegaze, dream-pop/rock, electronic-experimental band from Cincinnati, Ohio. The band currently consists of Maggie Cleary (vocals, guitar), Tim Koppenhafer (guitar, synths), Tony Squeri (drums, synths), and Mike Hühn (bass). The band has been active, recording material and performing since 2016.

www.marrband.bandcamp.com/

There are two disbanded groups called Marr:

(1) An experimental indie-rock band from Hamburg, Germany. (www.myspace.com/marrmusic)
(2) A rock band from Canada (pictured) (www.myspace.com/marr) Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.