As a Half-Orc I have Relentless Endurance:
Relentless Endurance When you are reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead. You can't use this feature again until you finish a long rest. (PHB p.42)
While wild-shaped "you retain the benefit of any features from your class, race, or other source and can use them if the new form is capable of doing so." (PHB p.68)
So, as a half-orc druid in wild shape when my temporary/wild-shape hit points drop to zero can I choose then to drop to 1 hit point without ever reverting form? Additionally, what happens to the "carry-over damage" that usually applies to a wild shape taking more damage than its current hit points?
Related: Does the half orc's Savage Attack work when wild shaped?
Best Answer
Yes you can
The rules for wildshape clearly state that you retain any benefits of features from your race if the new form is capable of using them. Since the Relentless Endurance feature does not implicitly or explicitly require any particular body parts (hands, for example) I see no reason why it should not be retained.
The rule on reverting says you automatically revert if you hit 0 hit points. Since your Relentless Endurance allows you to drop to 1 hp instead of dropping to 0, you never actually drop to zero and thus never revert.
... and there is no carry-over damage
The rule on carry-over damage says:
Since you did not revert or drop to 0 hit points, this rule does not apply.