Hard Rock: when you talk about it, you immediately think of Led Zeppelin and Deep Purple (as well as Cream and Free)...
I would like to suggest a few examples of lesser-known bands or those that are not directly associated with the genre.
7 - .C̤A̤C̤T̤ṲS̤ ̤ ̤O̤n̤e̤ ̤W̤a̤y̤ ̤or another ..1971 -- Full Album