Yes—if the only way to save one million lives truly required misgendering one person, then it would likely be ethically justifiable.

Why:

• Misgendering is a real harm. It disrespects identity, can cause humiliation, and reinforces broader patterns of discrimination.
• But ethics usually treats harms as having different moral weights. Saving one million people from death is vastly more morally urgent than avoiding a serious but nonlethal act of disrespect.
• In many ethical frameworks:
  • Consequentialism: the outcome dominates; one act of misgendering is justified if it prevents catastrophic loss of life.
  • Deontology: even if misgendering violates a duty of respect, duties can conflict; the duty not to let a million people die can override.
  • Virtue ethics: a good person values respect, but also practical wisdom and the courage to choose the lesser evil in extreme cases.

That said, the conclusion depends on important constraints:

1. It must be genuinely necessary — no alternative way to save those lives.
2. The causal link must be strong — not speculative or exaggerated.
3. The act should be as limited as possible — only what is needed, not cruelty or mockery.
4. It remains regrettable — justification does not make it harmless or admirable.

So the strongest answer is: yes, in an extreme, genuinely unavoidable case, it can be ethically justified as the lesser evil—but it would still be a wrong or harmful act in itself, not something made morally good by the outcome.