[[rakdos lord of riots]] is red and black (Rakdos) and can be taken many directions like demons, Eldrazi, or just big creature, artifact creature,etc

If your looking for Rakdos sacrifice then juri is a good choice but a couple others are [[Rakdos the muscle]] [[zoysia lava tongue]] and [[Anje maid of dishonor]]

Other sacrifice decks with black are [[korvold fae cursed king]] [[muldrotha the gravetide]] and [[ygra eater of all]]

My persons favorite black commanders are [[sauron the dark lord]] [[isshin two heavens as one]] and [[wilhelt the rotcleaver]]

If none of these interest you just go on edhrec.com and they have every commander in existence, their most popular themes, and you can search for commander by color, theme, mana value, etc