Defunct teams
The last team to fold in the NFL was the Dallas Texans, unrelated to the AFL's Dallas Texans that became the Kansas City Chiefs. As no proper helmets were used until the 1950s, leather helmets prior to this, just names and dates are listed.
Akron Pros(1920-26)
Brooklyn Lions(1926)
Buffalo All-Americans / Bisons / Rangers(1920-27, 1929)
Canton Bulldogs(1920-23, 1925-26)
Chicago Tigers(1920)
Cincinnati Celts(1921)
Cleveland Tigers/Indians(1920-21)
Cleveland Indians/Bulldogs(1923-25, 1927)
Columbus Panhandles/Tigers(1920-26)
Dayton Triangles(1920-29)
Detroit Tigers(1921)
Detroit Panthers(1925-26)
Detroit Wolverines(1928)
Duluth Kelleys/Eskimos(1923-27)
Evansville Crimson Giants(1921-22)
Frankford Yellow Jackets(1924-31)
Hammond Pros(1920-26)
Hartford Blues(1926)
Kansas City Blues/NFL_Cowboys_logo(1924-26)
Kenosha Maroons(1924)
Los Angeles Buccaneers(1926)
Louisville Breckenridges (a.k.a. "Brecks") (1921-23)
Louisville Colonels(1926)
Massillon Tigers(1920)
Milwaukee Badgers(1922-26)
Minneapolis Marines(1921-24)
Minneapolis Red Jackets(1929-30)
Muncie Flyers(1920-21)
New York Brickley Giants(1921)
New York Yankees(1926 1st AFL/1927-28 NFL)
Newark Tornadoes(1930)
Oorang Indians(1922-23)
Orange Tornadoes(1929)
Pottsville Maroons/Boston Bulldogs(1925-29)
Providence Steam Roller(1925-31)
Racine Legion(1922-24)
Racine Tornadoes(1926)
Rochester Jeffersons(1920-25)
Rock Island Independents(1920-25)
Staten Island Stapletons(1929-32)
St. Louis All Stars(1923)
Toledo Maroons(1922-23)
Tonawanda Kardex(1921)
Washington Senators(1921)

Brooklyn Dodgers/Tigers(1930-44)
Cincinnati Reds(1933-1934)
Cleveland Indians(1931)
St. Louis Gunners(1934)

Baltimore Colts(1947-50)
Boston Yanks/New York Bulldogs/New York Yanks/Dallas Texans(1944-1948/1949/1950-1951/1952)

Rejected franchises
Massillon Tigers(1920)
Syracuse Pros(1921)
Union Quakers of Philadelphia (1922)
Youngstown Patricians(1922)
Los Angeles Bulldogs
  • Replaced by Cleveland Rams due to travel concerns.
  • Rams would move to Los Angeles in 1946.
Pennsylvania Keystoners
  • Proposed merger of the Philadelphia Eagles and Pittsburgh Pirates.
  • A temporary merger happened in 1943, Steagles,
    due to player shortages as a result of World War II.
Buffalo Bills (AAFC)
  • Four NFL owners blocked the team's entry into the NFL.
    The current Buffalo Bills is unrelated.
Seattle Sea Lions and Seattle Kings
  • Two related early proposals for a team in Seattle.
    A Seattle team would either be via a relocation of the Buffalo Bills
    or by expansion.
  • Seattle Seahawks were chosen instead.
Orlando Suns
  • One of the bidders for the NFL's Central Florida team.
  • NFL chose the Tampa Bay Buccaneers instead.
Memphis Grizzlies
  • Members of the World Football League.
  • Unsuccessfully sued NFL to attempt to force admission (see: Mid-South Grizzlies v. NFL).
New Jersey Generals
Baltimore Bombers
Memphis Hound Dogs
St. Louis Stallions