delt designed the logo you see today when Schism Tracker starts up. The first draft of the logo posted to the forum was slanted, though most people liked the straight version better.
Prior to that (around 2006), the old placeholder "logo" in use was just Schism Tracker written in a script style, similar to Impulse Tracker.
Fun fact: Storlek painstakingly studied Impulse Tracker's startup dialog, holding a magnifying glass up to a laptop screen, and recreated the dialog pixel-by-pixel on another computer... and then after about an hour of blinding pixel-counting, realized that the logo was simply Brush Script MT.