Green’s Dictionary of Slang

1. an inferior or less well-known brand.

1913		letter in USA, Petitioner, Against Amer. Sugar Refining Co. 8 4262: Some eight or ten years ago, we did make an off brand of Granulated Sugar that we sold at five points under our regular Standard brand.
1926		Nat. Assoc. Retail Druggists Jrnl 43 1426/1: Often when I have suggested other articles or brands, the buyer comes back at me, and wants to know if I am making more profit on the ‘off brand.’ Folk are suspicious of unadvertised goods.
1963		M. Braly Shake Him Till He Rattles 53: The bread she was buttering was some off-brand, tasteless as sawdust.
2012		Pelecanos (con. 1972) What It Was 10: The bottle had been filled and refilled over the years with off-brands, its label faded to gray.

2. (US) a black person.

1992

Bentley & Corbett Prison Sl. 55: Off Brand Any non-white person.

3. (US black gang) a rival gangster.

1991

L. Bing Do or Die (1992) 64: ‘Ask him what he wants to do when he gets older.’ Diamond’s features slide into a grin. ‘Kill off-brands.’.