Jack Vermeulen is a level designer who worked for Sensor Based Systems, Inc.
Vermeulen is notable for creating the DeePsea editor for Doom, as well as its precursors such as DeeP97 and DeeP95 (often referred to as simply DeeP). DeeP95 existed on the DOS platform and allowed for the creation of Doom, Duke Nukem 3D, and Quake levels. DeeP97 was converted to the Windows 95 platform, but dropped support for Duke Nukem 3D due to the underwhelming demand for an editor for that game. All versions of DeeP are very limited in their support for Quake, most functionality was created to be able to rip textures from either Quake or Hexen II, though Sensor Based Systems, Inc. had some proprietary in-house utilities that allowed for the creation of some Quake levels. They considered these utilities to be too frustrating for the general public to use and therefore never released them. As such, though Vermeulen released some levels made with DeeP95 for Quake, the editors were mostly promoted to be used with games on the Doom engine.