1940 in comics

Year overall

 * Another boom year for the burgeoning American comic book industry, as Ace Comics, Columbia Comics, Farrell Publications, Holyoke Publishing, Novelty Press, and Street & Smith Comics all begin publishing.

January

 * Ace Comics (1937 series) #34 - David McKay Publications
 * Action Comics (1938 series) #20 - DC Comics
 * Adventure Comics (1938 series) #46 - DC Comics
 * All-American Comics (1939 series) #10 - DC Comics
 * Amazing Mystery Funnies (1938 series) #17 - Centaur Publications
 * Detective Comics (1937 series) #35 - DC Comics
 * Double Action Comics (1939 series) #2 - National Periodical Publications, consisting entirely of black and white reprints from early issues of More Fun Comics.
 * Feature Comics (1939 series) #28 - Quality Comics
 * Marvel Mystery Comics (1939 series) #3 - Timely Comics
 * More Fun Comics (1936 series) #51 - National Periodical Publications
 * Smash Comics (1939 series) #6 - Quality Comics

Debuts

 * Daring Mystery Comics (1940 series) #1 - Timely Comics
 * Flash Comics (1940 series) #1 - National Periodical Publications
 * Teen-Age Romances #1 - St. John Publications debuts January 14th

February

 * Ace Comics (1937 series) #35 - David McKay Publications
 * Action Comics (1938 series) #21 - DC Comics
 * Adventure Comics (1938 series) #47 - DC Comics
 * All-American Comics (1939 series) #11 - DC Comics
 * Daring Mystery Comics (1940 series) #2 - Timely Comics
 * Detective Comics (1937 series) #36 - DC Comics
 * Feature Comics (1939 series) #29 - Quality Comics
 * Flash Comics (1940 series) #2 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #4 - Timely Comics
 * More Fun Comics (1936 series) #52 - National Periodical Publications
 * Smash Comics (1939 series) #7 - Quality Comics
 * Whiz Comics #2, the first appearance of Captain Marvel — Fawcett

Spring

 * Batman (1940 series) #1 - DC Comics

March

 * Ace Comics (1937 series) #36 - David McKay Publications
 * Action Comics (1938 series) #22 - DC Comics
 * Adventure Comics (1938 series) #48 - DC Comics
 * All-American Comics (1939 series) #12 - DC Comics
 * Amazing Mystery Funnies (1938 series) #18 - Centaur Publications
 * Detective Comics (1937 series) #37 - DC Comics
 * Feature Comics (1939 series) #30 - Quality Comics
 * Flash Comics (1940 series) #3 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #5 - Timely Comics
 * Master Comics (1940 series) #1 - Fawcett Publications
 * Mystic Comics (1940 series) #1 - Timely Comics
 * More Fun Comics (1936 series) #53 - National Periodical Publications
 * Silver Streak Comics (1939 series) #3 — title acquired by Lev Gleason Publications
 * Smash Comics (1939 series) #8 - Quality Comics
 * Superman (1939 series) #4 cover dated Spring - National Periodical Publications

April

 * Ace Comics (1937 series) #37 - David McKay Publications
 * Action Comics (1938 series) #23 - DC Comics
 * Adventure Comics (1938 series) #49 - DC Comics
 * All-American Comics (1939 series) #13 - DC Comics
 * Amazing Mystery Funnies (1938 series) #19 - Centaur Publications
 * Daring Mystery Comics (1940 series) #3 - Timely Comics
 * Detective Comics (1937 series) #38 - DC Comics
 * Feature Comics (1939 series) #31 - Quality Comics
 * Flash Comics (1940 series) #4 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #6 - Timely Comics
 * Master Comics (1940 series) #2 - Fawcett Publications
 * More Fun Comics (1936 series) #54 - National Periodical Publications
 * Mystic Comics (1940 series) #2 - Timely Comics
 * Smash Comics (1939 series) #9 - Quality Comics

May

 * Ace Comics (1937 series) #38 - David McKay Publications
 * Action Comics (1938 series) #24 - DC Comics
 * Adventure Comics (1938 series) #50 - DC Comics
 * All-American Comics (1939 series) #14 - DC Comics
 * Amazing Mystery Funnies (1938 series) #20 - Centaur Publications
 * Daring Mystery Comics (1940 series) #4 - Timely Comics
 * Detective Comics (1937 series) #39 - DC Comics
 * Doc Savage Comics (1940 series) #1 - Street & Smith Publications
 * Feature Comics (1939 series) #32 - Quality Comics
 * Flash Comics (1940 series) #5 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #7 - Timely Comics
 * More Fun Comics (1936 series) #55 - National Periodical Publications
 * Smash Comics (1939 series) #10 - Quality Comics

Summer

 * All Star Comics (1940 series) #1 - DC Comics
 * Batman (1940 series) #2 - DC Comics

June

 * June 2: first publication of Will Eisner's "The Spirit Section", featuring debuts of the series The Spirit, Lady Luck and Mr. Mystic.
 * Ace Comics (1937 series) #39 - David McKay Publications
 * Action Comics (1938 series) #25 - DC Comics
 * Adventure Comics (1938 series) #51 - DC Comics
 * All-American Comics (1939 series) #15 - DC Comics
 * Amazing Mystery Funnies (1938 series) #21 - Centaur Publications
 * Daring Mystery Comics (1940 series) #5 - Timely Comics
 * Detective Comics (1937 series) #40 - DC Comics
 * Feature Comics (1939 series) #33 - Quality Comics
 * Flash Comics (1940 series) #6 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #8 - Timely Comics
 * Master Comics (1940 series) #3 - Fawcett Publications
 * More Fun Comics (1936 series) #56 - National Periodical Publications
 * Mystic Comics (1940 series) #3 - Timely Comics
 * Smash Comics (1939 series) #11 - Quality Comics
 * Superman (1939 series) #5 cover dated Summer - National Periodical Publications

July

 * Ace Comics (1937 series) #40 - David McKay Publications
 * Action Comics (1938 series) #26 - DC Comics
 * Adventure Comics (1938 series) #52 - DC Comics
 * All-American Comics (1939 series) #16 - DC Comics
 * Amazing Mystery Funnies (1938 series) #22 - Centaur Publications
 * Detective Comics (1937 series) #41 - DC Comics
 * Doc Savage Comics (1940 series) #2 - Street & Smith Publications
 * Feature Comics (1939 series) #34 - Quality Comics
 * Flash Comics (1940 series) #7 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #9 - Timely Comics
 * Master Comics (1940 series) #4 - Fawcett Publications
 * More Fun Comics (1936 series) #57 - National Periodical Publications
 * Mystic Comics (1940 series) #4 - Timely Comics
 * Smash Comics (1939 series) #12 - Quality Comics

August

 * Ace Comics (1937 series) #41 - David McKay Publications
 * Action Comics (1938 series) #27 - DC Comics
 * Adventure Comics (1938 series) #53 - DC Comics
 * All-American Comics (1939 series) #17 - DC Comics
 * Amazing Mystery Funnies (1938 series) #23 - Centaur Publications
 * Detective Comics (1937 series) #42 - DC Comics
 * Feature Comics (1939 series) #35 - Quality Comics
 * Flash Comics (1940 series) #8 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #10 - Timely Comics
 * Master Comics (1940 series) #5 - Fawcett Publications
 * More Fun Comics (1936 series) #58 - National Periodical Publications
 * Red Raven Comics (1940 series) #1 - Timely Comics
 * Smash Comics (1939 series) #13 - Quality Comics

Fall

 * All Star Comics (1940 series) #2 - DC Comics
 * Batman (1940 series) #3 - DC Comics

September

 * Ace Comics (1937 series) #42 - David McKay Publications
 * Action Comics (1938 series) #28 - DC Comics
 * Adventure Comics (1938 series) #54 - DC Comics
 * All-American Comics (1939 series) #18 - DC Comics
 * Amazing Mystery Funnies (1938 series) #24, last issue - Centaur Publications
 * Daring Mystery Comics (1940 series) #6 - Timely Comics
 * Detective Comics (1937 series) #43 - DC Comics
 * Feature Comics (1939 series) #36 - Quality Comics
 * Flash Comics (1940 series) #9 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #11 - Timely Comics
 * Master Comics (1940 series) #6 - Fawcett Publications
 * More Fun Comics (1936 series) #59 - National Periodical Publications
 * Smash Comics (1939 series) #14 - Quality Comics
 * Superman (1939 series) #6 - National Periodical Publications

October

 * Ace Comics (1937 series) #43 - David McKay Publications
 * Action Comics (1938 series) #29 - DC Comics
 * Adventure Comics (1938 series) #55 - DC Comics
 * All-American Comics (1939 series) #19 - DC Comics
 * Detective Comics (1937 series) #44 - DC Comics
 * Feature Comics (1939 series) #37 - Quality Comics
 * Flash Comics (1940 series) #10 - National Periodical Publications
 * Human Torch (1940 series) #2 - Timely Comics
 * Marvel Mystery Comics (1939 series) #12 - Timely Comics
 * Master Comics (1940 series) #7 - Fawcett Publications
 * More Fun Comics (1936 series) #60 - National Periodical Publications
 * Smash Comics (1939 series) #15 - Quality Comics

November

 * Ace Comics (1937 series) #44 - David McKay Publications
 * Action Comics (1938 series) #30 - DC Comics
 * Adventure Comics (1938 series) #56 - DC Comics
 * All-American Comics (1939 series) #20 - DC Comics
 * Detective Comics (1937 series) #45 - DC Comics
 * Feature Comics (1939 series) #38 - Quality Comics
 * Flash Comics (1940 series) #11 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #13 - Timely Comics
 * Master Comics (1940 series) #8 - Fawcett Publications
 * More Fun Comics (1936 series) #61 - National Periodical Publications
 * Smash Comics (1939 series) #16 - Quality Comics
 * Superman (1939 series) #7 - National Periodical Publications

Winter

 * All Star Comics (1940 series) #3 - DC Comics
 * Batman (1940 series) #4 (DC Comics) — first appearance of Gotham City

December

 * Ace Comics (1937 series) #45 - David McKay Publications
 * Action Comics (1938 series) #31 - DC Comics
 * Adventure Comics (1938 series) #57 - DC Comics
 * All-American Comics (1939 series) #21 - DC Comics
 * Detective Comics (1937 series) #46 - DC Comics
 * Feature Comics (1939 series) #39 - Quality Comics
 * Flash Comics (1940 series) #12 - National Periodical Publications
 * Marvel Mystery Comics (1939 series) #14 - Timely Comics
 * Master Comics (1940 series) #9 - Fawcett Publications
 * More Fun Comics (1936 series) #62 - National Periodical Publications
 * Smash Comics (1939 series) #17 - Quality Comics

Specials

 * Mutt & Jeff (1939 series) #2 - All-American Comics
 * New York World's Fair Comics (1939 series) #2 - National Periodical Publications

First issues by title

 * All Star Comics, cover-dated Summer, published by All-American Publications.
 * Batman, cover-dated Spring, published by DC Comics.
 * Big Shot Comics, cover-dated May, published by Columbia Comics.
 * Daring Mystery Comics, cover-dated January, published by Timely Comics.
 * Doc Savage Comics published by Street & Smith Publications.
 * Flash Comics cover dated January, published by National Periodical Publications.
 * Green Hornet, cover-dated December, published by Helnit.
 * Jackpot Comics, cover-dated Spring, published by MLJ Magazines, Inc.
 * Master Comics, cover-dated March, published by Fawcett Publications.
 * Red Raven Comics, cover-dated August, published by Timely Comics.
 * Shield-Wizard Comics, cover-dated Summer, published by MLJ Magazines, Inc.
 * Walt Disney's Comics and Stories, cover-dated October, published by Dell Comics.
 * Wow Comics, cover-dated Winter, published by Fawcett Comics.
 * Zip Comics, cover-dated June, published by MLJ Magazines, Inc.

Initial appearances by character name

 * Catwoman in Batman #1 (Summer), created by Bill Finger and Bob Kane, published by DC Comics.
 * Doctor Hormone in Popular Comics #54 (August), published by Dell Comics.
 * The Flash (Jay Garrick) in Flash Comics #1 (January), created by Gardner Fox and Harry Lampert, published by National Periodical Publications.
 * Hawkman (Carter Hall) in Flash Comics #1 (January), created by Gardner Fox and Dennis Neville, published by National Periodical Publications.
 * The Joker in Batman #1 (Summer), created by Jerry Robinson (concept), Bill Finger, and Bob Kane, published by DC Comics.
 * Justice Society of America in All Star Comics #3 (Winter), created by Sheldon Mayer and Gardner Fox, published by DC Comics.
 * Robin in Detective Comics #40 (June), created by Jerry Robinson (concept), Bill Finger, and Bob Kane, published by DC Comics.
 * Silver Streak in Silver Streak Comics #3 (March), created by Joe Simon, published by Lev Gleason Publications.