Serum - VST for FL Studio, Ableton Live, and many other VST supported DAWs. Heavily utilized in EDM.
Guitarix - Guitarix is a simple Linux Rock Guitar Amplifier for https://alternativeto.
Omnisphere - Piano, pad and synth VST for DAW's.
Rakarrack - Rakarrack is a richly featured multi-effects processor emulating a guitar effects pedalboard.
Korg Legacy Collection - Korg Legacy Collection is a suite of VST instruments that acts as an audio plugin software for integrating synthesizers and effects units into your digital audio workstation.
ToneLib GFX - The perfect custom tone with a complete guitar studio in your computer