Jackson Arley Martínez Valencia (; born 3 October 1986) is a Colombian former professional footballer who played as a striker. 

He started his career with Independiente Medellin in 2004 and becoming the league's top scorer in 2009, before being signed by Chiapas in January 2010. He spent three years with the Mexican side before moving to Portugal to play for Porto, where he was the Primeira Liga's top scorer in all three of his seasons with the club. In July 2015, Martínez joined Atlético Madrid for €35 million, and six months later Guangzhou Evergrande of China for €42 million. He  suffered an ankle injury in late 2016 that ruled him out for two years, before ending his career back in Portugal with Portimonense in 2020.

Martínez represented Colombia 40 times between 2009 and 2015, scoring nine goals for the country. He played for them at the Copa América in 2011 and 2015, as well as the 2014 FIFA World Cup, where he scored two goals against Japan.

Club career

Independiente Medellín
Born in Quibdó in the Chocó Department, Martínez joined Independiente Medellín's youth academy in 2001 until being called up to the first team for the 2004 Finalización. He made his debut on 3 October 2004, his 18th birthday, in a 2–2 draw against Junior. His first professional goal came roughly a month later in a 1–1 draw against Deportivo Pereira on 7 November. This was the last matchday of the regular season and his goal sealed Medellin's qualification into the playoffs. 

With three goals in the Finalizacion playoffs, Martinez looked like he had a bright future ahead, but the following seasons were very slow-paced. From 2005 to 2007, he scored 12 goals, only 2 per tournament. But the 2008 season was his breakthrough season under manager Santiago Escobar, where he scored 11 goals as Medellin finished runner-up in December 2008 to América de Cali.

In January 2009, Martinez scored his first career hat-trick in a 4–0 victory against Peñarol in the 2009 Copa Libertadores first stage. Martinez began the 2009 Apertura campaign in great form, scoring 4 goals in 4 matches. However, he suffered an injury in March 2009 before a Copa Libertadores match against America de Cali, which saw him miss the rest of the 2009 Apertura campaign, as Medellin had a rough campaign and finished in last place. Despite this setback, he bounced back and was the top goalscorer of the 2009 Torneo Finalizacion with 18 goals, including braces against Real Cartagena, América de Cali, Atlético Huila, and Envigado, while leading El Poderoso to its fifth league title with a goal in each leg of the finals against Huila.

Chiapas
Martínez attracted interest from South Korean club Ulsan Hyundai as well as Argentine clubs San Lorenzo de Almagro and Racing Avellaneda. He initially signed a pre-contract with Ulsan Hyundai, but the club could not reach an agreement with him. As a result, Martínez was eventually signed by Chiapas from the Liga MX on a three-year-contract for an undisclosed fee in January 2010. 

He scored his first two goals with the club on 30 January in a 2–2 draw against Tigres UANL. Two weeks later, he scored against Pachuca, and then scored three in the next three games. He ended his first season with the club, the 2010 Torneo Bicentenario, with nine goals, placing him fourth in the top scorer's table. In August 2010, he had an ankle operation and was ruled out for a month. In the following season, the 2010 Apertura, he didn't perform well, only scoring two in fourteen appearances, but scored a match winner against Atlas in the penultimate matchday to give Chiapas a spot in the playoffs, where they were eliminated by eventual champions Santos Laguna. 

In the 2011 Clausura, Martinez missed most of the season due to an injury he suffered in the Copa Libertadores match against Alianza Lima on 27 January, which ruled him out for almost three months. In his return on 30 April, he scored a brace in a 4–1 victory against Querétaro, but his team finished bottom of the table. However, in the Copa Libertadores, Chiapas had much better form and Martínez was a key player for them, scoring in both legs of the round of 16 encounter against Colombian club Junior to help his team go through on away goals. In the first leg at Estadio Víctor Manuel Reyna, he scored in a 1–1 draw, and then scored a double in the second leg, despite being shown a red card during the 3–3 draw in Barranquilla. Chiapas were eventually eliminated by Paraguayan side Cerro Porteño in the quarter finals, with the Colombian playing in the second leg.

In the Apertura 2012 season, he scored eight goals, including braces against San Luis and Pumas UNAM, and added to his tally by scoring once in each leg of the playoffs against Santos, but Chiapas were eliminated. Martínez was named captain of the squad at the beginning of the Clausura 2012 season, where he scored eight goals, with two braces again, this time in victories against Atlas and Queretaro. In the playoffs, Chiapas were paired up with Santos again, and Martinez scored a brace in the first leg, but his team were not able to get revenge and were eliminated by Santos again for the third time in eighteen months.

Porto

2012–13 season

On 7 July 2012, Porto announced that they had signed Martínez on a four-year contract worth €8.8 million, in addition to setting a €40 million release clause. On 11 August, he played his first competitive match in the 2012 Supertaça against Académica de Coimbra, also scoring his first goal. He scored in the 90th minute, which gave Porto their 19th victory of the tournament, and was named as the man of the match.

Martínez scored his first league goal on 25 August with a Panenka penalty against Vitória de Guimarães, with Porto winning the game 4–0. On 22 September against Beira-Mar, he scored a bicycle kick from a chipped pass by fellow countryman James Rodríguez. Against rivals Sporting CP, he scored a back-heel volley in a 2–0 win. In the Champions League group stage on 24 October, Martínez scored his first two goals in European competitions, during a match which ended in a 3–2 victory for Porto against Dynamo Kyiv. Martínez continued his goal scoring streak in a 2–1 victory over Estoril on 28 October, assisting Silvestre Varela and scoring the game winner five minutes later. On 2 November, he scored two more goals in a 5–0 victory against Marítimo. He was named the SJPF Player of the Month for October and November. In December, Spanish sports newspaper Marca ranked him number 8 in a list of the Top 10 South American players of 2012.

Martínez scored five goals in January 2013: the only goal against Nacional on 5 January,  in O Clássico against rivals Benfica on 13 January, a double ten days later in a 3–0 away victory against Vitoria Setubal, and against Gil Vicente on 28 January. By the halfway point of the league season, he had scored 14 goals in the first 15 league games, surpassing Falcao's numbers of 10 goals in 14 games. On 2 February, he scored a hat-trick against Vitória de Guimarães, which included two headers, making it his first hat-trick for Porto. He scored a brace on 23 February, including a penalty and a volley, to help Porto turn around a 0–1 deficit into a 2–1 victory against Rio Ave at Estádio do Dragão. He was named the February SJPF Player of the Month. In the final match of the league season against Paços de Ferreira, Martínez sealed the 2–0 victory after scoring the second goal and assuring Porto's third consecutive league title, undefeated and one point ahead of rivals Benfica. The goal also marked his 26th goal in the league, securing him the Bola da Prata. Following his debut season in Europe, ESPN noted Martínez as one of the best signings for the 2012–13 season.

2013–14 season

In the 2013 Supertaça Cândido de Oliveira, Martínez scored the second goal in a 3–0 victory against Vitória de Guimarães at the Estádio Municipal de Aveiro, claiming his second Portuguese SuperCup in a row.

In the opening league match against Vitória de Setúbal on 18 August, Martínez scored the third goal in a 3–1 win. He continued the season in excellent form, adding four more goals in the next four matchdays. On 6 October, he scored a double against recently promoted Arouca in a win by the same score. He scored the only goal of the game in the Europa League round of 16 first leg against Napoli on 13 March, and Porto eventually qualified to the next round by winning 3–2 on aggregate. On 19