Question: Which American comics artist, worked for both Marvel Comics and DC Comics, and made the three-issue Skull & Bones?

Context articles: Rick Leonardi
Dan Spiegle
Ed Hannigan
Paul Gulacy
John Byrne (comics)
Don Newton
Jim Mooney
Amanda Conner
Skull &amp; Bones (DC Comics)
Sam Glanzman

Rick Leonardi (born August 9, 1957) is an American comics artist who has worked for various series for Marvel Comics and DC Comics, including "Cloak and Dagger", "The Uncanny X-Men", "The New Mutants", "Spider-Man 2099", "Nightwing", "Batgirl", "Green Lantern Versus Aliens" and "Superman".
 He has worked on feature film tie-in comics such as "Star Wars: General Grievous" and "Superman Returns Prequel" #3.
Dan Spiegle (December 10, 1920 – January 28, 2017) was an American comics artist and cartoonist best known for comics based on movie and television characters across a variety of companies including Dell Comics, DC Comics, and Marvel Comics.
Ed Hannigan (born August 6, 1951) is an American comics artist, writer, and editor for both Marvel Comics and DC Comics.
Paul Gulacy (born August 15, 1953) is an American comics artist best known for his work for DC Comics and Marvel Comics, and for drawing one of the first graphic novels, Eclipse Enterprises' 1978 "Sabre: Slow Fade of an Endangered Species", with writer Don McGregor.
 He is most associated with the 1970s martial-arts / espionage series, Marvel's "Master of Kung Fu".
John Lindley Byrne ( ; born July 6, 1950) is an American comics artist and writer.
 Since the mid-1970s, Byrne has worked on many major superheroes.
 Byrne's better-known work has been on Marvel Comics' "X-Men" and "Fantastic Four" and the 1986 relaunch of DC Comics' "Superman" franchise, the first issue of which featured comics' first variant cover.
 Coming into the comics profession as penciller, inker, letterer and writer on his earliest work, Byrne began co-plotting the "X-Men" comics during his tenure on them, and launched his writing career in earnest with "Fantastic Four" (where he also served as penciler and inker).
 During the 1990s he produced a number of creator-owned works, including "Next Men" and "Danger Unlimited".
 He scripted the first issues of Mike Mignola's "Hellboy" series and produced a number of "Star Trek" comics for IDW Publishing.
 In 2015, Byrne and his X-Men collaborator Chris Claremont were entered into the Will Eisner Award Hall of Fame.
Don Newton (November 12, 1934 — August 19, 1984) was an American comics artist.
 During his career, he worked for a number of comic book publishers including Charlton Comics, DC Comics, and Marvel Comics.
 He is best known for his work on The Phantom, Aquaman, and Batman.
 Newton also drew several Captain Marvel/Marvel Family stories and was a fan of the character having studied under Captain Marvel co-creator C. C. Beck.
James Noel Mooney (August 13, 1919 – March 30, 2008) was an American comics artist best known for his long tenure at DC Comics and as the signature artist of Supergirl, as well as a Marvel Comics inker and Spider-Man artist, both during what comics historians and fans call the Silver Age of comic books.
 He sometimes inked under the pseudonym Jay Noel.
Amanda Conner is an American comics artist and commercial art illustrator.
 She began her career in the late 1980s for Archie Comics and Marvel Comics, before moving on to contribute work for Claypool Comics' "Soulsearchers and Company" and Harris Comics' "Vampirella" in the 1990s.
 Her 2000s work includes "Mad" magazine, and such DC Comics characters as Power Girl and Atlee.
Skull & Bones is a three-issue prestige format mini-series by Ed Hannigan published in 1991 by DC Comics.
Samuel Joseph Glanzman (December 5, 1924 – July 12, 2017) was an American comics artist, best known for his Charlton Comics series "Hercules", about the mythological Greek demigod; his biographical war stories about his service aboard the U.S.S. "Stevens" for DC Comics and Marvel Comics; and the Charlton Comics "Fightin' Army" feature "The Lonely War of Willy Schultz", a Vietnam War-era serial about a German-American U.S. Army captain during World War II.