Silver Age of Comic Books
Collectibility

Title & Issue
Cover date
Publisher
Relevance
Detective Comics #225
Nov. 1955
DC
First appearance of Martian Manhunter.
Showcase #4
Oct. 1956
DC
First appearance of the Silver Age Flash (Barry Allen). First Silver Age comic.
Showcase #9
Aug. 1957
DC
First of two pilot issues for the feature "Superman's Girl Friend, Lois Lane".
Adventure Comics #247
April 1958
DC
First appearance of the Legion of Super-Heroes.
Adventure Comics #260
May 1959
DC
First appearance of the Silver Age Aquaman.
Action Comics #252
May 1959
DC
First appearance of Supergirl (Kara Zor-El), cousin to Superman.
Showcase #22
Oct. 1959
DC
First appearance of Green Lantern (Hal Jordan).
The Brave and the Bold #28
March 1960
DC
First gathering of DC's superheroes as the Justice League of America.
Richie Rich #1
Nov. 1960
Harvey
Richie Rich gets his own title.
Showcase #30
Feb. 1961
DC
First of four pilot issues for Aquaman.
The Brave and the Bold #34
March 1961
DC
First appearance of Silver Age Hawkman and Hawkgirl.
The Flash #123
Sept. 1961
DC
Reappearance of the Golden Age Flash. Introduction of Earth-Two.
The Fantastic Four #1
Nov. 1961
Marvel
First appearance of the Fantastic Four.
Tales to Astonish #27
Jan. 1962
Marvel
First appearance of Henry Pym, the future Ant-Man.
The Incredible Hulk #1
May 1962
Marvel
First appearance of the Hulk.
The Fantastic Four #5
July 1962
Marvel
First appearance of Dr. Doom.
Amazing Fantasy #15
Aug. 1962
Marvel
First appearance of Spider-Man (Peter Parker).
Journey into Mystery #83
Aug. 1962
Marvel
First appearance of Marvel's Thor (Thor Odinson / Donald Blake).
Tales to Astonish #35
Sept. 1962
Marvel
First appearance of Ant-Man (Henry Pym).
Doctor Solar, Man of the Atom #1
Oct. 1962
Gold Key
First appearance of Doctor Solar.
Magnus, Robot Fighter #1
Feb. 1963
Gold Key
First appearance of Magnus, Robot Fighter.
Tales of Suspense #39
March 1963
Marvel
First appearance of Iron Man (Tony Stark).
Strange Tales #110
Jul. 1963
Marvel
First appearance of Doctor Strange.
Justice League of America #21
Aug. 1963
DC
Reappearance of the Golden Age Justice Society of America.
The X-Men #1
Sept. 1963
Marvel
First appearance of the X-Men and Magneto (comics).
The Avengers #1
Sept. 1963
Marvel
First gathering of Marvel's superheroes as the Avengers.
The Avengers #4
March 1964
Marvel
Reappearance of Captain America (Steve Rogers) from the Golden Age of Comic Books.
Daredevil #1
April 1964
Marvel
First appearance of Daredevil.
Detective Comics #327
May 1964
DC
"New Look" Batman and Robin.
The Brave and the Bold #54
June 1965
DC
First appearance of the Teen Titans.
Detective Comics #359
Jan. 1967
DC
First appearance of Batgirl (Barbara Gordon).
Green Lantern #76
April 1970
DC
"The New Green Lantern / Green Arrow" tackles social issues.

Question: Who was the publisher of this comic?
Answer: Martian Manhunter introduced in Detective Comics #225 predates Showcase #4 by almost a year.