Ronny Deila (born 21 September 1975) is a Norwegian football manager and former player, who is the current head coach of Atlanta United in Major League Soccer.

[4] His first two seasons as head coach saw the club struggle against relegation,[3][4] but his attacking philosophy began to bear fruit as Strømsgodset started to record higher finishes in the Norwegian league.

Having previously visited Manchester City, Barcelona and Ajax to acquire further knowledge, he then after the end of the season in 2013 travelled to Borussia Dortmund and Liverpool to study their coaching and training methods.

[4] However, Deila was beginning to attract foreign attention, and Strømsgodset had given him a new contract to run until 2016 in order to head off interest from Swedish champions Malmö who had unsuccessfully attempted to poach him in January.

[4] Despite this new contract, various media reports surfaced in the first week of June linking Deila to the vacant managerial post at Scottish champions Celtic.

[12][13][3][4] He signed a 12-month rolling contract with the club, describing his appointment as a "magnificent honour" before stating his desire to deliver "attacking, exciting and entertaining football.

Deila described Collins as a "first-class coach" and stated that he "has ideas on football which are very similar to mine so I am sure he will be a great addition to my team.

"[14] After going unbeaten on a pre-season tour in Austria,[15] Deila's first competitive match as manager of Celtic, a Champions League qualifying tie away against KR Reykjavik on 15 July 2014, ended in a 1–0 win for the Scottish club.

UEFA punished the Polish club by awarding the game 3–0 to Celtic, levelling the aggregate score at 4–4 and seeing the Scottish champions progress on away goals.

[21] Deila's second league match, and his first game at Parkhead, saw Celtic defeat Dundee United 6–1 in a performance that BBC Sport described as being "full of drive, skill, belief and… goals.

[28] In the league, Celtic beat second placed Aberdeen 4–0 on 1 March to go six points clear with a game in hand and a vastly superior goal difference.

Kris Commons and James Forrest were Celtic's goalscorers, whilst Stefan Johansen won the Man of the Match award.

[38] Vålerenga continued to perform poorly into Deila's second season, and a run of only one win in seven games saw them languishing in eighth place at the end of October 2018.

[43] Under Deila's guidance, NYCFC won MLS Cup 2021, as they defeated Portland Timbers in the final match with a 4–2 win on penalties, after a 1–1 scoreline in extra time.

[45] In his first game on 22 July, the team scored a late equaliser to draw 2–2 at home to Gent, having been down to ten men since the 15th-minute dismissal of Alexandro Calut.