Energy management skills

Warrior Skills
To compensate for lack of energy regeneration and having elite energy management skills, many Warrior skills are instead fueled by adrenaline.

Ranger Skills
In addition to skills that provide energy, Rangers have Expertise which reduces the cost of many skills

Monk Skills
Monk skills don't provide much energy management, except through signets which do not cost energy. There are a few skills that reduce energy cost for a period of time. Often monks will use a secondary profession for energy management.

Necromancer Skills
In addition to skills that provide energy, Necromancers have Soul Reaping which provides energy on deaths. Many Necromancer energy management skills benefit allies instead of the caster.