From 1968 to 1970, Neal Adams did a dramatic series of covers for the DC comic Tomahawk. Many of them feature the title hero tied up in some creative way. Several of the earlier issues (#116 - 118) have a limited palette, likely making them really stand out on the newsstand.
Tomahawk #116, June 1968.
Tomahawk #117, August 1968.
Tomahawk #118, October 1968.
Tomahawk #119, December 1968.
Tomahawk #121, April 1969.
Tomahawk #123, August 1969.
Tomahawk #124, October 1969.
Tomahawk #125, December 1969.
Tomahawk #126, February 1970.
Tomahawk #127, April 1970.
Tomahawk #128, June 1970.
Tomahawk #130, October 1970.