The two gave college football fans a thrill at the Rose Bowl last season, with Darnold passing for 453 yards and five touchdowns in the Trojans' 52-49 victory over the Nittany Lions. Barkley rushed for 194 and had three scores in the contest.
LSU's Derrius Guice joins Darnold and Barkley in the backfield on the first team. Guice served as the backup for the last two seasons to Leonard Fournette, who was selected with the fourth overall pick of the 2017 draft by the Jacksonville Jaguars.
Washington State guard Cody O'Connell and Utah punter Mitch Wishnowsky were selected to the first team after being All-Americans last year.
The first-team defense is led by two players who were postseason All-Americans in 2016 in Houston defensive tackle Ed Oliver and Alabama defensive back Minkah Fitzpatrick.
Florida State's secondary was well represented with cornerback Tarvarus McFadden and safety Derwin James, who missed most of last year with a knee injury.
The ACC led all conferences with seven players on the first team, followed by the SEC (five) and the Big Ten (four) and Pac-12 (four).
Quarterback -- Sam Darnold, sophomore, Southern California.
Running backs -- Saquon Barkley, junior, Penn State; Derrius Guice, junior, LSU.
Tackles -- Orlando Brown, junior, Oklahoma; Connor Williams, junior, Texas.
Center -- Billy Price, senior, Ohio State.
Tight end -- Mike Gesicki, junior, Penn State.
Wide receivers -- James Washington, senior, Oklahoma State; Christian Kirk, junior, Texas A&M.
All-purpose player -- Quadree Henderson, junior, Pittsburgh.
Kicker -- Daniel Carlson, senior, Auburn.
Ends -- Harold Landry, senior, Boston College; Bradley Chubb, senior, North Carolina State.
Tackles -- Ed Oliver, sophomore, Houston; Dexter Lawrence, sophomore, Clemson.
Linebackers -- Arden Key, junior, LSU; Josey Jewell, senior, Iowa; Azeem Victor, senior, Washington.
Cornerbacks -- Tavarus McFadden, junior, Florida State; Jaire Alexander, junior, Louisville.
Safeties -- Derwin James, junior, Florida State; Minkah Fitzpatrick, junior, Alabama.
Punter -- Mitch Wishnowsky, junior, Utah.
Quarterback -- Lamar Jackson, junior, Louisville.
Running backs -- Nick Chubb, senior, Georgia; Bo Scarbrough, junior, Alabama.
Tackles -- Mike McGlinchey, senior, Notre Dame; Jonah Williams, sophomore, Alabama.
Guards -- Will Hernandez, senior, UTEP; Braden Smith, senior, Auburn.
Center -- Frank Ragnow, senior, Arkansas.
Tight end -- Troy Fumagalli, senior, Wisconsin.
Wide receivers -- Calvin Ridley, junior, Alabama; Courtland Sutton, junior, SMU.
All-purpose player -- Jaylen Samuels, senior, North Carolina State.
Kicker -- Eddy Pineiro, sophomore, Florida.
Ends -- Tyquan Lewis, senior, Ohio State; Rashan Gary, sophomore, Michigan.
Tackles -- Christian Wilkins, junior, Clemson; Vita Vea, junior, Washington.
Linebackers -- Micah Kiser, senior, Virginia; Tegray Scales, senior, Indiana; Cameron Smith, junior, Southern California.
Cornerbacks -- Duke Dawson, senior, Florida; Iman Marshall, junior, Southern California.
Safeties -- Quin Blanding, senior, Virginia; Godwin Igewbuike, senior, Northwestern.
Punter -- JK Scott, senior, Alabama.