Question: Hellhound first appeared as the opponent of a fictional character created by what 2 people?

Context paragraphs:
Catwoman: Catwoman is a fictional character appearing in American comic books published by DC Comics, commonly in association with the superhero Batman.  Created by Bob Kane and Bill Finger, the character made her debut as "the Cat" in "Batman" #1 (Spring 1940).

Red Sonja (film): Red Sonja is a 1985 Dutch-American sword and sorcery action film directed by Richard Fleischer.  The film introduces Brigitte Nielsen as the title character with Arnold Schwarzenegger, Sandahl Bergman, Ronald Lacey, Ernie Reyes, Jr., Paul L. Smith and Pat Roach in supporting roles.  The film features the sword-wielding Marvel Comics character Red Sonja, created by Roy Thomas, who first appeared in Marvel's "Conan the Barbarian" series (#23) in 1973.  The film's character of Red Sonja was based on Red Sonya of Rogatino, a character created by Robert E. Howard appearing in his short story "The Shadow of the Vulture" (1934).  The film acknowledges that it was "based on the character created by Robert E. Howard" in the introductory credits.

Popeye: Popeye the Sailor is a cartoon fictional character created by Elzie Crisler Segar.  The character first appeared in the daily King Features comic strip, Thimble Theatre, on January 17, 1929, and Popeye became the strip's title in later years; Popeye has also appeared in theatrical and television animated cartoons.

Bouncer (Fox Feature Syndicate): The Bouncer is a fictional character who appeared in comic books published by Fox Feature Syndicate.  A superhero created by writer Robert Kanigher and artist Louis Ferstadt, he first appeared in "The Bouncer" (no number, September 1944).  His final appearance was in "The Bouncer #14" (January 1945).  He is the first comic book character created by Kanigher.

Hellhound (comics): Hellhound is the name of two fictional characters that are DC Comics supervillains.  The first Hellhound appeared as an opponent of Catwoman.

Magneto (Atlas Comics): Magneto is a fictional character created by Stan Lee and Jack Kirby.  The character first appeared in "Strange Tales" #84, in May 1961, just before Atlas Comics became Marvel Comics.  Even though the character name and creators are the same as the modern Marvel's Magneto, the Atlas Comics character is not related to Marvel's mutant.

Doc Stearn...Mr. Monster: Doc Stearn...Mr. Monster is a fictional character comic book superhero created by Michael T. Gilbert, most recently published by Dark Horse Comics.  The character first appeared in Pacific Comics "Vanguard Illustrated" #7 (July 1984).  Later the character graduated to his own monthly series "Doc Stearn...Mr. Monster" from Eclipse Comics.  Mr. Monster was derived from an old 1940's character created by Fred Kelly who appeared only twice in 1940s Canadian comic books ("Triumph Comics" #31, 1946, and "Super-Duper Comics" #3, 1947).  After trademarking Mr. Monster, Gilbert heavily revised the character creating a Horror/Humor hybrid which often featured heavy satire of both the horror genre and superhero comics in general.

Dorothy Spinner: Dorothy Spinner is a fictional character created by Paul Kupperberg and owned by DC Comics.  She was a former member of the Doom Patrol with the ability to bring imaginary beings to life.  She first appeared in "Doom Patrol" vol.  2, #14 (November 1988) as a background character until she was made a full member a few issues later.

Marada (comics): Marada, the She-Wolf is a fantasy comic book fictional character created for Epic Comics by writer Chris Claremont and English artist John Bolton.  She first appeared in "Epic Illustrated" #10 (Feb. 1982).  The story was originally planned for the character of Red Sonja, Conan's sometime partner, but had to be changed due to issues surrounding the then-in-production "Red Sonja" movie with Brigitte Nielsen.  Claremont moved the historical milieu from the Hyborian Era to the Roman Empire, and changed her hair from red to silver.  This change of character from Red Sonja to Marada resulted in some dispute over ownership of the character.  Since Marada's adventures were first published in the creator-owned series "Epic Illustrated", the rights to her character were eventually given to writer Claremont and artist Bolton.

Night Hawk (comics): Night Hawk is a fictional character created by John James Brearley Garbutt and appeared in the boys' paper Nelson Lee in the early 1930s.  The hero was rich scientist Thurston Kyle who built an armored, winged flying suit to fight crime.  The character first appeared in The Nelson Lee Library (New Series) No. 11, April 5, 1930, "The Night Hawk!" , anonymous (Garbutt).

Supporting paragraphs: Hellhound (comics) Catwoman
Answer: Bob Kane and Bill Finger