Matrix
Matrix (Supergirl (Pocket Universe), 1988-1996, 2000-2002) appears in 62 issues in grailworth's catalog, and was first published in 1988.
Every appearance we value
Action Comics (1938) 4 issues
Adventures of Superman (1987) 15 issues
The Darkstars (1992) 2 issues
JLA (1997) 2 issues
JLA Secret Files (1997) 1 issue
The New Titans (1988) 2 issues
Showcase '95 (1995) 1 issue
Supergirl (1994) 4 issues
Valor (1992) 2 issues
Zero Hour: Crisis in Time (1994) 4 issues
Character appearances from the Grand Comics Database, CC BY-SA 4.0.