Art Blakey's 1958 Moanin' is the classic hard bop album. It has Benny Golson (ts), Lee Morgan (t), Bobby Timmons (p), and Jymie Merritt (b). This is probably essential listening just for being most typical of a particular style or mode.
A Night at Birdland (1954), though, is even better. It has Clifford Brown, Horace Silver, and Lou Donaldson, and is in a more boppish mode, with "Night in Tunisia."
This list will amount to a discography of essential jazz music, with some omissions and biases, of course.