Holmar Orn Eyjolfsson is an Icelandic footballer who plays as a defender for Levski Sofia in the Bulgarian First League. He is the son of Eyjolfur Sverrisson, former Iceland international and manager.

Holmar signed for West Ham United on 6 July 2008 from Icelandic team HK, where he previously made 19 first team appearances. In October 2009, Holmar signed on loan for Cheltenham Town, making his full debut on 3 October 2009 in the 1-1 home draw against Notts County. He returned to West Ham in November 2009 having made four appearances for Cheltenham. In January 2010, Holmar joined K.S.V. Roeselare, on loan. He played 16 games for Roeselare but was unable to prevent the club's relegation to the Belgian Second Division. He then left West Ham in May 2011 when his contract ran out without having played a first-team game for them. Holmar signed for German 2. Bundesliga team, VfL Bochum on 19 June 2011. In 2014, he signed with Rosenborg, earning 38 appearances and 2 goals by October 2015. On 1 September 2017, Holmar signed a 4-year loan contract with Bulgarian club Levski Sofia.

Capped previously at U-16 and U-17 level, Holmar was a key player at the 2007 European U-17 Championship and, although Iceland failed to make it beyond the group stage, was named by UEFA as one of the tournament's players to watch in future. Those finals in Belgium also saw him show his versatility as he played in a holding midfield role, although he prefers to play at the back. Holmar made his U21 debut in November 2007 while still in the U19's and had an instant impact, helping Iceland to their first win of the 2009 European Championship qualifying campaign with a 2-1 victory in Belgium. He was in the starting line-up for the next three games. Though Iceland failed to make the play-offs, he became a regular starter in the U21 team. He scored his first international goal in a 9 October 2011 European Championship qualifier, which Iceland won 8-0 against San Marino. Holmar received his first call-up to the Iceland national team in May 2012 in a friendly against Sweden.