Example embodiments may provide a CMOS image sensor and example methods of forming the same. Example embodiment CMOS image sensors may include a transfer gate insulating pattern between a transfer gate and an active region. A photodiode region and/or a floating doped region may be in the active region at either side of the transfer gate. The transfer gate insulating pattern may include a first part adjacent to the photodiode region and/or a second part adjacent to the floating doped region. The first part may be thicker than the second part.