What are these creatures that the Avengers are fighting off in the "Infinity War" trailers? Are they aligned with or controlled by Thanos?
(And as @Möoz confirms in the comments, they are indeed aligned with Thanos)
The Outriders were a race of genetically engineered parasite-assassins which solely to serve their master/creator. They live binary lives, they either complete their task or they fail.
The Outriders look incredibly similar to the alien that the Black Panther is fighting, both with four arms, no eyes and fangs.