Summoned EnderDragon don't have Boss Bar.

Not a duplicate of MC-83239.
MC-83239 is labeled "fixed".
This bug is specific to the /summon command

/summon EnderDragon

Reopen please.

Won't be fixed:

I'm seeing this as Dinnerbone telling player to respawn the dragon for fighting. Map makers use the Dragon bar for other uses with summon. Could we verify this? Because I know a lot of map use that health bar to display things unrelated to the Dragon.

Nope, the bossbar is for the fight, not for the dragon alone.

Even still, it would be helpful to mark this as "Works as Intended" or something since map makers will be searching for the term "summon". However, I'm not sure Dinnerbone understands he removed a good feature outside Survival.

Confirmed for 15w41b

Confirmed for 15w42a

Confirmed for 15w44b! Another problem with the bossbar is that when you add the tag "CustomName:<name>" then "<name>" isn't over the bar (same for withers)

EDIT: Then I saw what Dinnerbone said.....

@unknown: MC-83571.

WAI per Dinnerbone's comments on MC-83239.