Does anyone know what brand toilet this is?

BigErl

I couldn’t find any numbers or markings. It’s a one piece. The tank lid slants down towards the back. The fill valve has a 1/2” shank. It’s hooked up with a faucet supply line.

rick in Alaska

Most of the time the info is in the tank on the back wall. I don't recognize that one though.
Rick

delta T

If I had to guess, I'd say it's a Toto. Not sure though without some numbers

Alan (California Radiant) Forbes

Makes me think Porcher.

FriendlyFred

I would go with a "TOTO AQUIA MS654114MF" or it's cousin.