Moving using only one leg is known as unipedal movement.
Many bivalvia and nearly all gastropoda molluscs have evolved only one foot.
Through accidents (i.e. amputation) or birth abnormalities it is also possible for an animal, including humans, to end up with only a single leg.
Their tracks in texts and sources", in Analecta Septentrionalia: Beiträge zur nordgermanischen Kultur- und Literaturgeschichte, ed.
by Wilhelm Heizmann, Klaus Böldl and Heinrich Beck (Berlin/London/New York: De Gruyter), pp.