ESPN's Mel Kiper Jr. lists Harris as the third-best inside linebacker in the draft.
Harris had 79 tackles this season, 12.5 of which were for a loss. He also had 5.5 sacks and a pair of forced fumbles.
While Harris won't return, fellow inside linebacker and Alabama's leader in tackles, Henry To'oTo'o, said last week that he would come back for his senior season.
Safety Jordan Battle will also return.
Cornerback Jaylin Armour-Davis, offensive tackle Evan Neal, defensive lineman Phidarian Mathis, running back Brian Robinson Jr. and receivers Jameson Williams, John Metchie III and Slade Bolden all previously announced that they would be turning pro.
Alabama has lost several players to the transfer portal as well, including reserve linebacker Drew Sanders (Arkansas), backup quarterback Paul Tyson (Arizona State) and tight end Jahleel Billingsley (Texas).
The Crimson Tide added former LSU All-America defensive back Eli Ricks and former Georgia Tech All-ACC running back Jahmyr Gibbs via the portal.