Rigg has been named in the England Under-17 World Cup squad, having already scored two goals in seven games for the first team this season.
He is also the club’s youngest outfield debutant, at 15 years and 203 days.
“He is this warrior-like character, a personality and internal mechanism,” Mowbray told BBC Radio Newcastle.
He wants to win every tackle, every 5-a-side, every contest he’s in, which is pretty unique in a footballer.
“I shouldn’t really say it, but it’s that Roy Keane-esque type of ‘nastiness’.
“He’s a nice kid, but not so much of a nice kid when he’s got his boots on and is on the pitch.”
Both Rigg and Southampton’s trio of Jayden Meghoma, Samuel Amo-Ameyaw, and Tyler Dibling are the only players not to be on the permanent books of top-flight clubs to make the group for the competition, which kicks off in Indonesia this month.
“It’s richly deserved,” Mowbray said. “I can’t name the squad of players, or who plays, or are around the first team, but Chris warrants being around our first team every day.
“He warrants getting on the pitch in football matches to try to affect them and I’m pretty sure in the next few years he’ll warrant a regular starting place and potentially captains it.
“I hope he can stay here and fulfil for some years to help the club progress and do well.”
