Terrance Casey Brennan (born August 11, 1948) is an American comic book writer.
During the 1970s, he wrote for Warren Publishing's black-and-white horror-comics anthologies Creepy and Eerie, and Vampirella. He also wrote for DC Comics' House of Mystery and Archie Comics' Red Circle Sorcery.
In the 1980s, Brennan campaigned to have depictions of smoking in comics banned, which led then-Gov. Bill Clinton of Arkansas to issue a proclamation designating January 1990 as "T. Casey Brennan Month".
Kitaro's Sideshow, podcast in Hebrew from Israel, featured songs by T. Casey Brennan in episodes #36 and #37.
One of T. Casey Brennan's early publishers was alleged UFO contactee Daniel Fry, who published his essays in Understanding magazine; examples from October 1974 and September 1988 issues are posted on the Internet.