The Omega Man (1971), directed by Boris Sagal.
I have an inordinate fondness for this one because I saw it at the theater when I was in high school. It also helps to be a fan of science fiction, Charlton Heston, and "siege" stories. There is something exciting about a siege, probably due to childhood nightmares: "they're out there, trying to break in and get us." You can make fine films about that, for example The Seven Samurai (1954).
The best scenes are the early ones of the dead city, with the semi-mad scientist in his "honky paradise", arrogant and callous. The rest looks very 1971 (as it should, of course!): jogging suits, proud afro hairstyles, hip racial banter, discreet female nudity. The light action music is lush and sometimes strangely chosen.
It's something like a zombie apocalypse plot and we have more childhood survival fantasy: the apocalyptic joys of the deserted city, where would I live, what gear would I need, how to generate electricity... Exciting stuff.
The director did mostly TV work and the film has that look, despite the wide aspect ratio. I suspect Heston had become undirectable by this point, just doing it the way he wanted: shirtless and bitterly sarcastic, much like Taylor in Planet of the Apes (1968).
Still his star power provides mythic energy: the army scientist cracking up from loneliness and guilt ("There are no phones ringing!"). His final tragedy is that in the end, he would rather suit up and exterminate The Family than escape with the survivors.
Misc notes:
Remember this one when you make lists of your desert island films: Neville wants Woodstock. All those people.
Why is he immune? Did he really inject himself with the serum after the helicopter crash? It has always looked to me like he didn't.
The Family is multi-racial and evil.
I noticed a Rear Window (1954) quote this time: like Miss Lonelyhearts, he can't convince himself an imaginary companion is real.
What's with his leisure clothes: puffy sleeves, silk scarves, flamboyant smoking jacket? Well, why not? End of the world and all. Maybe it is a reaction to the dour robes The Family favors
The good guys were ready with the stadium lights pretty quickly.
Why is Lisa sad when she looks at the calendar?
Mathias tells him: "Your bad dream is over". And The Family vanishes as he dies. That's weird.
Final scene: do none of the survivors wonder what happened to Richie?
I reviewed this previously, and thinking of "last man and woman" stories was hoping for The World, the Flesh and the Devil (1959) on disc. It has since become available on DVD (and Blu-ray), and I found better editions of The Last Man on Earth (1964) with Vincent Price, like Omega Man based on Richard Matheson's I Am Legend.
Available on Blu-ray.