Megalian

 Megalian, or Heady as it is known as in Mega Man Battle Network 6, is a virus from the Mega Man Battle Network series. It has an aura around it that blocks attacks below a certain damage amount. It also shoots its head towards its target.

Megalian/MegalianA/HeadyA
 Megalians are tan with red bands and have a blue aqua aura that protects them. Weak to elec.

Megalian2/MegalianH/HeadyH
 Megalian2 s are green with yellow bands and have a red heat aura that protects them. Weak to aqua.

Megalian3/MegalianW/HeadyW
 Megalian3 s are purple with gray bands and have a green wood aura that protects them. Weak to heat.

MegalianE
 MegalianEs are light-blue with green bands and have a yellow elec aura that protects them. Weak to wood.

HeadyE
 HeadyEs are gray with gray-blue bands. They are similar to MegalianEs.

RareHeady
 RareHeadys are blue with red-purple bands and have a yellow aura that protects them.

RareHeady2
 RareHeady2s are gold with light-blue bands and have a yellow aura that protects them.

Source
Sprite images found at Sprites INC