I can’t imagine Superman '78 without her. Her Lois is still the definitive portrayal for me. In some ways she’s the bridge character for the audience and her reactions to the guy flying around in blue tights and a cape are so genuine.
https://youtu.be/Czvv01yL0nA
Margot had the guts to call out the producers on their BS firing Richard Donner on Superman II, though they got back at her reducing her role to a cameo in III.
With her mental health issues, I hope she found some peace in the past few years.