Giving your forum an entirely new look and feel is easy — just download one of these great themes! There are even themes for the admin control panel.
Browsing All Themes

Fully responsive, modern & multicolor theme for MyBB 1.8 (Documentation included)
这是一个中文版的Emerald Dark主题,主要用于解决部分中文用户在使用本模板过程中遇到的翻译错误

Emre KRMN vBulletin default style theme for mybb 1.8.x

eXe is a mobile compatible and desktop mybb theme.Applies to Mybb versions 1.8.X

Responsive and multicolor ACP theme in Flat Design

Flatty - A nice & simplistic flat theme for MyBB.

Focus is a clean and Elegant Flat MyBB theme which can be used by all sort of community users, one of the cool features of this theme is shrinking header on scroll. Focus MyBB Theme has been tested thoroughly on all browsers.
This theme is based off of the Wordpress theme Frontier.
Classic material theme

Fresh & Girly coloured theme for MyBB. Just a simple transformation from the default one.
Green Noise
by sirev
Green noise theme under blue-grayed backgrounds.

Another Hacking Forum Theme

A dark semi transparent gaming skin

Black and natural for lovers.

Impulse Dark is the sister theme of Simple MyBB Variant Theme