Temporarily implanted electrocorticographic (ECoG) electrodes provide cortical electrical activity data during deep brain stimulation (DBS) surgery. Accurate localization of ECoG electrodes in 3D space is required for the recorded data to be useful in research, but these electrodes are only implanted intraoperatively. During surgery, the only imaging modality available is fluoroscopy, which produces a 2D rather than 3D image. Current approaches require postoperative (postop) computed tomography (CT) volumes to register with intraoperative fluoroscopic (fluoro) images, allowing the possibility of concurrent electrode placement and 3D visualization. We present a domain-knowledge end-to-end (DKE2E) pipeline to automate 3D localization of ECoG electrodes from preoperative (preop) CT volumes, fluoro images, and brain volume masks from magnetic resonance imaging (MRI). The DK-E2E achieves a mean±std euclidean distance from the ground-truth of 13.67±6.13 mm, enabling future work that produces real-time localization of ECoG electrodes during DBS surgery.