One of the best backend theme available for Odoo with extensive change in look & feel
Odoo Backend Theme v11
Theme Armstrong is Odoo Business Theme with Modern style, Extremely customizable, Clean and Fully Responsive.
Theme Snowy is a Odoo theme with advanced ecommerce feature, extremely customizable and fully responsive
Theme Flexible is exceptionally configurable.
Bootswatch Lumen
Html5 Responsive E-Commerce And Multi-Purpose theme
Elegant Module for Website Shop
*** Odoo 10/11 community backend theme ***
This module provides feature for changing layout of theme.
Bring enterprise look and feel to Odoo community
Odoo 11 Silent Material Theme
Clean & Modern Multipurpose Theme
Odoo Backend Theme
HTML5 Bootstrap Odoo Theme for Mobile eCommerce
HTML5 Bootstrap Ecommerce Theme for Furniture Industry
If want more space, use this theme