Secco's Stand: Oasis (Jojo's Bizarre Adventure Part V)
Sheen the God (Jimmy Neutron); when he creates quicksand from the ground
Certain Earth Release users (Naruto)
Earthbenders (Avatar: The Last Airbender)
Dioxin (The New Heroes)
Daolon Wong (Jackie Chan Adventures)
Freddy Krueger (A Nightmare on Elm Street)
Due to the acidic venom that his body constantly exudes, Dioxin (The New Heroes) cannot even stand still in one place for long or the ground beneath his feet will begin to liquefy.
Zaku (Naruto) using airwaves to soften the ground via high pressure liquification.
Daolon Wong's (Jackie Chan Adventures) favored technique for incapacitating foes is by softening the ground around them into a liquid and then hardening it. This can be done on any surface, including soil, stone or concrete.
Lucy Heartfilia (Fairy Tail) using Aqua Metra to liquify the earth to make it flow like the sea and waves.