  There are at least 125 Galactic pulsar wind nebulae (PWNe) that have been
discovered from radio wavelengths to TeV gamma-rays, the majority of which were
first identified in radio or X-ray surveys. An increasing number of PWNe are
being identified in the TeV band by ground-based air Cherenkov Telescopes such
as HESS, MAGIC, and VERITAS such that they constitute the dominant source class
of Galactic TeV emitters. Combining available MeV-GeV data with observations in
the TeV band is critical for precise characterization of high-energy emission
from the relativistic particle population in PWNe, thus revealing the
capability to produce a significant fraction of the detected Galactic CR flux.
However, MeV-GeV PWN counterparts are still largely lacking even after 12 years
of continuous observation of the entire sky. Less than a dozen PWNe are
currently identified by the Fermi-LAT in the MeV-GeV band. Most PWNe are
located along the Galactic plane embedded within the prominent, diffuse
Galactic gamma-ray emission, which makes these sources difficult to disentangle
from the bright diffuse background. We present a systematic search for
gamma-ray counterparts to known PWNe in the 300MeV - 2TeV energy band using
11.5 years of Fermi-LAT data. For the first part of this search, we target the
locations of PWNe previously identified across the electromagnetic spectrum
that are not powered by pulsars previously detected by the Fermi-LAT as
pulsating gamma-ray signals, which includes 6 Fermi PWNe and 7 Fermi PWN
associations. We report the analysis of 58 total regions of interest and
provide all firm and tentative detections along with their morphological and
spectral characteristics. There are 11 unidentified gamma-ray sources that we
classify as firm PWN counterparts, which doubles the PWN population detected by
the Fermi-LAT, and 22 gamma-ray sources that are PWN candidates.
