Heean Ko (고희안) is a jazz pianist, composer and bandleader who leads two long-running groups: the band Prelude, formed in Boston as a six-piece by Korean and Korean-American students at Berklee College of Music, and the Koheean Trio (고희안 트리오), a piano trio that has played in Seoul since 2009. His releases print his name as Heean Ko and the trio as Koheean Trio, with his family name and given name run together. Korean newspapers and the Korean Music Awards write Ko Heean, and Discogs lists the spellings Hee An Ko and Ko Hee An Trio.

MusicBrainz gives his birth year as 1976, and the label text for his 2016 album says he was born and raised in Tongyeong, the port city on Korea's south coast; his day and month of birth are not published. By his own account to the Korea JoongAng Daily in January 2006, he studied landscape at Korea University and expected to work in that field, with the piano as a hobby. He left the university against his parents' wishes for Berklee in Boston and then completed a master's program in music at New York University. Money Today described him in 2018 as a Berklee alumnus. In a 2020 interview with Newstomato he said he had listened to Count Basie since childhood and had studied swinging pianists closely ever since.

Prelude came first. The Korea JoongAng Daily wrote in January 2006 that its six members met as music majors at Berklee and formed the band in 2002, while the label text for his later albums gives 2003. Three of the six were raised in the United States and three, including Ko, came from Korea. The paper named the drummer Abraham Lagrimas Jr., from the Philippines, the saxophonists Charles Lee and Richard Rho, both of whom consider themselves Korean-Americans, and the bassist Jinbae Choi. It called Ko, then 30 by its count, the leader and pianist. The band's first album, Croissant, came out on Sony BMG in December 2005 and, according to the paper, sold more than 1,000 copies in Korea within a month, which it called very high for a young Korean jazz market. It also reported that the Blue Note club in Manhattan had confirmed a booking for the band in May 2006 (Yonhap gave April), but in 2008 the Busan Ilbo quoted Ko saying that the 2006 Blue Note booking had been set and then cancelled. Bugs lists further Prelude albums from 2008 to 2025, and by 2016 the label text for his trio album counted eight in all.

Much of Prelude's later work crosses into Korean traditional music, which Money Today pointed to in 2018 when it wrote that Ko leads the band while forming a united front with gugak. The album Fly In (January 2014, Sony Music Korea) sets Korean folk songs for a jazz band with the sori vocalist Youngrang Jeon (전영랑), and Discogs credits Ko with piano and composition on it. Korean Men (2017, AkdangEban) is a record with the folk singer Lee Heemoon (이희문) and the group Nom Nom (놈놈). Fly-In Vol. 2 (December 2020) reworks the popular songs that Korean writers call "jass", the mix of folk song and imported swing that flourished in 1930s and 1940s Seoul.

The Koheean Trio is his own band for straight-ahead and original piano-trio jazz. The label texts give its start as 2009 and say it played every Monday at the Seoul club Cheonnyeon-dongan for about four years. The first album, Standards (2012), was recorded in three hours with the bassist 김인영 and the drummer Woongwon Han (한웅원). Standards II, recorded live at the club on November 11, 2013 and released in March 2014, introduces the bassist Yongdoe Jeong (정용도), who has worked with Han in the trio since. The third album, A Land of Blue Sky (2016), recalls his childhood in Tongyeong, and the fourth, Dancing Without Moving (December 2017), is an hour of ten of his own pieces recorded in a single performance before an audience of 50 in a basement space in Samcheong-dong, which Bugs picked as an Album of the Month for January 2018.

From 2017 the trio began touring Japan, playing clubs in Kyushu that include Riverside and Five Pennies in Fukuoka, Band Wagon in Shimonoseki and Jazz First in Kumamoto. On June 30, 2019, in heavy rain, it recorded a live album at Jazz First in Yatsushiro, with an engineer and equipment brought from Korea; the label text and Newstomato call it the first live album by a Korean jazz band recorded in a Japanese jazz club. Live at Jazz First, the fifth album, was released on July 16, 2020, and Newstomato reported a release concert at the Sejong Center Chamber Hall in Seoul scheduled for August 14, 2020. The sixth album, Live at Backstage, was recorded on January 15, 2024 at the Fukuoka club Backstage, which the label text calls a venue with a history of fifty years, after seven Japan tours. Its nine originals include tributes to Chick Corea, Keith Jarrett, Claude Bolling and Barry Harris.

The trio and Ko have been nominated three times for the Korean Music Awards. At the 16th awards, held at the Guro Arts Valley Theater on February 26, 2019, the trio was nominated for Best Jazz and Crossover Performance for Dancing Without Moving, and the duo album Dear Chopin with the saxophonist Hyunpill Shin was nominated for Best Crossover Album. At the 18th awards in 2021 the trio was nominated again in the performance category for Live at Jazz First; the prize went to Soojin Suh for Colorist. The sources found do not say whether the 2019 nominations led to a win.

Dear Chopin (June 2018) started a long partnership with Shin, a fellow Berklee alumnus. The two improvise on Chopin pieces as a duo of saxophone and piano with no rhythm section, and in the Money Today interview of August 2018 they said they were not reinterpreting Chopin so much as adding their own breath to the score. Three more records followed under the names Shin Hyunpill & Heean Ko or Shin Hyunpill & Ko Heean: Dear Schubert (2020), the original-music EP Iceland (2022) and Dear Mozart (2024).

His recent albums have widened the trio's frame. The Heean Ko Hawaii Trio, billed Koheean Hawaii Trio on streaming services, grew from a 2005 concert in Hawaii with the drummer Abe Lagrimas Jr., whom he had met at Berklee and who played in Prelude, and the bassist Shawn Conley, and the plan to record together took eighteen years to realize. The album Pink Island, recorded in front of an audience at the Hawaii Public Radio studio in 2023, came out on December 21, 2023, and Hawaii Public Radio announced a release concert at Blue Note Hawaii for June 11, 2024. Silver Lining (December 3, 2024), his solo piano album, was recorded live on the afternoon of November 26, 2023 at the T1 Pavilion of the Cultural Reserve Base in Seoul, where a broken heater left the hall cold enough to stiffen his fingers. A Jazz Docent newsletter listed it among its memorable straight-ahead jazz albums of 2024. The most recent album, Connection (February 5, 2026), is billed Koheean Trio X Son Moeun and brings the Paris-based violinist Moeun Son into the trio; the label text says the group recorded all eight tracks in three hours in the summer of 2025, while she was in Korea for concerts.

Beyond his own releases, Discogs credits him with piano on Lee Jung-sik's Oldies & Memories (2007), with keyboards on the drummer Woongwon Han's live album Catch the Moment (2014, which also features Hyunpill Shin) and with piano on J_ONE Memento Mori (2010) by the piri and sheng player Jin Yun-kyung. He is credited as a composer on the singer Oh Ji-eun's album 3 (2013). No teaching post, official website or longer biography by the artist turned up in the sources found, so this profile follows his recordings and the press that covered them.

His trio plays in a mainstream piano-trio tradition and writes almost all of its newer repertoire. The 2012 and 2014 albums are all standards, the later ones all originals, and the label texts hear a New Orleans feel in "Western Grip" and "Nigeria", salsa in "Habana", a waltz close to Bill Evans in "Dancing Without Moving", a Chick Corea-like modernity in "An Eccentric Person" and a Keith Jarrett-like gospel mood in "The Cure." In 2020 Ko said the fifth album put the trio's swing feel in front, and that its pieces came out of improvised interplay and travel memories, such as a first trip to Nigeria, more than from a chosen genre.

The trio prefers to record live. Four of its first six albums are live recordings, and so is every one of them from the fourth onward. Ko said that letting the mistakes remain is part of making the result jazz-like, and his bassist Yongdoe Jeong described the trio's music as the kind that walks a path where it might go wrong. When Money Today reviewed Dear Chopin in 2018, the reporter wrote that without the names he would have taken the pianist for a New York artist, and compared the duo's refinement to Bill Evans on piano and John Coltrane on saxophone. Outside the trio, his writing with Prelude and his gugak projects, which draw on sori and folk song, give the other half of his career a crossover identity.