The UK's Daily Express newspaper used to publish the Jeff Hawke science fiction strip. It was very popular and lasted for over 19 years, ending in 1974. There were 69 separate stories, with an average of 94 strips in each story.
Many consider it one of the most best science fiction strips ever published. The artwork is excellent, and the dialogue and plots are sophisticated. It was a strip for adults. It is far superior to the Batman, Superman and the other super hero rubbish. This Wikipedia article gives the full story and a list of episodes.
The Jeff Hawke strip is very popular in Italy and the Scandinavian countries. In the UK Titan Books published two books containing a total of nine stories. These can be bought from Amazon. Don't be put off by the lurid covers.
Overlord (collects "Overlord", "Survival", "Wondrous Lamp" and "Counsel for the Defence", 128 pages, February 2008, Titan Books. ISBN 1845765974)
The Ambassadors (collects "The Ambassadors", "Pastmaster", "The Immortal Toys", "The Gamesman" and "A Test Case", 128 pages, July 2008, Titan Books. ISBN 1845765982)
A better source of the Jeff Hawke stories is the Jeff Hawke Club which is publishing all 69 stories in bound volumes. Read this for more information.