The 1937-D "3 Legged" Buffalo Nickel is unique type of error which remains very popular with collectors. It may in fact be the most widely known error coin, along with the 1955 Double Die Lincoln Cent. The "3 Legged" Buffalo Nickel error takes its name from the fact that the  American Bison which appears on the reverse of the coin appears to have only three legs.

The error was caused by extensive die polishing on the reverse of the coin. The polishing was done to remove clash marks from the die, with the removal of the leg accidental. The mistake was not realized until most of the coins had already reached circulation.

Pieces are in demand in all grades, but especially so in mint-state. This error is often collected as a regular variety, as the reason for its popularity is obvious. A similar error exists for 1936-D, with 3 ½ legs, much scarce but less publicized.