Again, kinda based on neytirix's take on Endermen
Originally a pencil drawing. I scanned it and refined the drawing into this.

The Ender Dragon is the final stage of queen Endtroids, and is the sole member of a colony capable of reproduction. Endermen will fiercely protect her for this reason, as a colony cannot survive without a queen. It is hypothesized that multiple colonies, and thus queens, exist, though only one has been observed thus far.

Though she has an Ender Pearl, and is therefore capable of teleportation, the Ender Dragon travels mainly via flight. We have noted that when not in flight, she walks in a manner similar to earthly fowl.

The Ender Dragon does not regularly hunt like Endermen do; she relies largely on prey brought to her by them, and only hunts when her protectors are unsuccessful. Like all adult Endtroids, the queen produces Ender Acid, though she not only uses it to nourish her young, but also as a means of defending the colony. She will often spray acid from her mouth, or regurgitate a globule that splashes into a volatile mist. The acid is roughly 76% stronger than perchloric acid, making it a mere deterrent against other End fauna, but extremely hazardous to earthly life, especially when coming into contact with skin. It's possible that the acid can be used in alchemy, but further research is underway.

The Ender Dragon, like all fauna in the End, hydrates herself by drinking from acid ponds. Water is similarly dangerous to her like other End-native life.

Unlike Endermen, which only attack humans defensively, the Ender Dragon will attack humans unprovoked. It's likely she does this due to our unfamiliar, foreign scent, which makes her see us as a threat regardless of whether any actual attempts to harm her are made. Unfortunately, she does not always acknowledge our presence, so attacks by her are fairly unpredictable.