Starting in November of 1907 in a strip called A. Mutt, before a year was out Jeff would be introduced and the strip would be changed to Mutt & Jeff for the rest of it’s 77 year run.
The first successful daily comic strip in the form we know today, Mutt & Jeff was a pair consisting of the dim-witted Mutt and the scheming and possibly insane Jeff and the various hair-brained get-rich-quite ploys and adventures Jeff cooked up.
They first appeared in comics in Famous Funnies # 1 in 1933, and others after that, but found their first more lasting home at All-American Comics, which was soon absorbed by DC comics, and where Mutt & Jeff would stay for 103 issues in a comic that was made up entirely of reprints of the newspaper strip, which by the time of the comics 1939 debut amounted to over 10,000 strips to draw from!
After issue 103 DC dropped Mutt & Jeff and they were picked up by Dell comics who started doing original stories, a policy that was carried on by Harvey, Harvey would published Mutt & Jeff Comics until 1965.
The strip would go on until 1985.