Style ORGAN from VisareTone™ is a free virtual music instrument for Windows inspired by famous Classic Organ.
Soft Glow Organ is a free Vintage theater organ rompler vst plugin. And it uses samples from a 1960s electric organ and synthesizer-style controls to produce warm sounds with modern effects.
The Mini-Chord is a free digital chord organ VST instrument inspired by 1970s electric organs which often included a Chord Organ to go along with the traditional keyboard. Use familiar organ sounds and create brand new ones using the tempo-synced effects.
Drawbox is a free Hybrid Organ Synthesizer VST instrument.
Orpheus is a free strings / organ VST instrument audio plugin.