Mullen warming up for Adelaide United in 2010
|Full name||Daniel John Mullen|
|Date of birth||26 October 1989|
|Place of birth||Adelaide, South Australia, Australia|
|Height||1.87 m (6 ft 2 in)|
|Playing position||Centre Back / Right back|
|2013||→ Melbourne Victory (loan)||9||(0)|
|2014–2015||Western Sydney Wanderers||4||(0)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 6 March 2015.
† Appearances (Goals).
Daniel John Mullen (born 26 October 1989) is an Australian footballer who currently plays for the Newcastle Jets. His natural position is at centre back but he plays regularly at right back at club level. Daniel is the cousin of Matthew Mullen and son of former Socceroo Joe Mullen. In his first game for Australia he became the first Socceroo to wear a 3 digit number wearing 107 against Kuwait on 6 March 2009.
Mullen joined United for the 2008–09 A-League season. On 26 July 2008 he made his debut for Adelaide United in a 0–0 against Newcastle Jets in the Pre-Season Cup. He has since gone on to win a place in the team in the league and also featured against Kashima Antlers in the AFC Champions League. He played in Adelaide's Champions league semi final's 1st leg 3–0 victory over Uzbekistan outfit Bunyodkor and was surely the best game in his short career.
In November 2008 Daniel signed a new two year deal with Adelaide keeping him at the club until the end of the 2010–11 season. Mullen began to hold down a regular starting spot at right back for Adelaide including starting the inugral FIFA Club World Cup game for the South Australian team in which he scored the equalising goal against Waitakere United. Mullen scored his first league goal for Adelaide with a powerful header in the 3–2 victory over North Queensland Fury in Townsville in Round 4. He had some trouble holding a spot the first team squad with Robert Cornthwaite and Iain Fyfe regularly used at centre back. 
Western Sydney Wanderers
On 3 February 2014 he signed, along with Golgol Mebrahtu, with Western Sydney Wanderers. However, since there were no spaces remaining in the club's A-League squad, Mullen was only eligible to participate in Western Sydney Wanderers' 2014 AFC Champions League campaign during the 2013–14 season. On 18 March 2014, following a long term injury to Golgol Mebrahtu, Mullen was added to Western Sydney Wanderers' A-League squad. Mullen parted ways with the Wanderers in 30 January 2015.
- "Barbiero and Mullen hold their own on big stage". Adelaide United. 9 October 2008. Retrieved 12 January 2009.
- "Reds re-sign Mullen". A-League. 27 November 2008. Retrieved 12 January 2009.
- "Dodd heads Adelaide through". 12 December 2008.
- "Mullen's season in doubt". A-League. 12 January 2008. Retrieved 12 January 2009.
- Adelaide United defender Daniel Mullen set to join Chinese club Dalian Aerbin Goal.com
- "Mebrahtu and Mullen become Wanderers". Football Federation Australia. 3 February 2014.
- "Daniel Mullen added to A-League squad". Football Federation Australia. 18 March 2014.
- "Western Sydney Wanderers and Daniel Mullen Part Ways". Western Sydney Wanderers. 30 January 2015. Retrieved 30 January 2015.
- Mullen: A young Aussie on Chinese shorts FIFA.com