Gu Do-hyung official photo - South Korean actor, star of Backdoor

Gu Do-hyung

ActorSouth Korean

BIOGRAPHY

Gu Do-hyung (구도형, also romanised Koo Do-hyeong and Gu Do-hyeong) is a South Korean actor. Four credits are on the public record, and the shape they make is one this site has now seen several times on the Korean side: supporting parts in large broadcast dramas, and a leading part in a small queer one.

The earliest is an undated single episode credit as Jin-hyuk in The Substitute (대리수능). Then Villains Everywhere (빌런의 나라), a twenty four episode family drama on KBS2 that ran from 19 March to 24 April 2025, where Gu Do-hyung plays a student president. Then The Practical Guide to Love (미혼남녀의 효율적 만남), twelve episodes on JTBC from 28 February to 5 April 2026, produced by SLL and adapted from a webtoon, with Han Ji-min and Park Sung-hoon leading. Gu Do-hyung plays Jun-hyung.

Seven weeks after that finished came Backdoor (백도어), a boys’ love web series produced by SUKFILM and released on YouTube between 31 May and 21 June 2026. Gu Do-hyung plays Seo Ji-hyuk, one of the two leads, opposite Jang In-kyu as Kwon Do-yoon. The premise is an office romance: an anonymous stranger saves Do-yoon from a crisis at work, and the rescuer turns out to be the privileged new colleague he likes least.

TMDB holds no birth date, no birthplace and no biography for this actor. Two social handles are listed on the record and are not published here, for the reason given in the editor notes. A Wikipedia search returned unrelated Korean film results.

BLGLFlix editorial view

Twenty four episodes on KBS2. Twelve on JTBC, opposite two of the better known names in Korean television. Both supporting. Then a lead, in five episodes, on YouTube.

That sequence is the Korean situation stated as a career rather than as an industry statistic, and it cuts both ways. On one side it confirms what every Korean page on this site has found: BL here is made small, made fast and put on a free platform, seven weeks after the same actor was on a national broadcaster. On the other side it shows what BL actually offers a working Korean actor, which is the thing the broadcasters were not offering. A leading role.

Set that against Thailand, where the direction of travel runs the other way. A GMMTV lead becomes a studio asset, gets paired, gets a slate, and moves from queer series into mainstream productions on the same channel. In Korea nobody is being built into a star through BL, because the productions are too small to build anyone. What BL provides is a first chance to carry something.

The rhythm is worth noticing too. The Practical Guide to Love ended on 5 April 2026. Backdoor began on 31 May. Two months between a JTBC romcom and a YouTube BL web series, with no visible barrier between the two. Korean actors are not choosing a lane. There is only one pool of work, and the BL productions are simply the smallest jobs in it.

PROFILE DETAILS

Native Name
구도형
Real Name
Gu Do-hyung
Nickname
Koo Do-hyeong, Gu Do-hyeong
Profession
Actor
Nationality
South Korean
Debut
2025 — Villains Everywhere (빌런의 나라, 2025), earliest dated credit
Years Active
2025-present
Languages
Korean

FILMOGRAPHY — TV SERIES (1)

Backdoor (2026) official poster — Korean short-form office BL web series from SUKFILM starring Jang In-gyu
Backdoor
2026
Main Role

TRIVIA

  • Supporting roles on KBS2 and JTBC, then a leading role in a BL web series on YouTube.
  • Only seven weeks separate the end of the JTBC drama and the start of Backdoor.
  • Villains Everywhere ran twenty four episodes, the longest credit on the record.
  • The Practical Guide to Love is adapted from a webtoon and led by Han Ji-min and Park Sung-hoon.
  • Sources disagree on Backdoor’s episode count, giving either five or thirteen.
  • The name appears in three romanisations on record.

FREQUENTLY ASKED QUESTIONS

Who is Gu Do-hyung

A South Korean actor (구도형) with four credits on record, best known on this site as Seo Ji-hyuk, one of the two leads in the 2026 BL web series Backdoor.

What is Backdoor

A boys’ love web series produced by SUKFILM and released on YouTube between 31 May and 21 June 2026. Gu Do-hyung and Jang In-kyu lead as Seo Ji-hyuk and Kwon Do-yoon, in an office romance premise.

How many episodes does Backdoor have

The series record gives five and the actors’ own credits give thirteen. BLGLFlix reports both figures rather than choosing between them, and the count should be rechecked from an official source.

What else has Gu Do-hyung appeared in

Villains Everywhere (빌런의 나라, 2025), a twenty four episode KBS2 family drama, and The Practical Guide to Love (미혼남녀의 효율적 만남, 2026), a twelve episode JTBC romcom adapted from a webtoon. An undated single episode credit for The Substitute also appears. None carries a queer classification, so none has a page here.

How close together are the credits

The Practical Guide to Love finished on 5 April 2026 and Backdoor began on 31 May 2026, seven weeks later.

Written and verified by Renkaze · Last updated 3 September 2026

Biographical details and any photograph on this page come from TMDB and the sources named in our editorial notes. This product uses the TMDB API but is not endorsed or certified by TMDB. BLGLFLIX is an independent reference site with no affiliation to the person profiled or their agency, and does not publish speculation about anyone’s private life. Full copyright, correction and takedown policy: Disclaimer.

Sources

4 sources

Every factual claim on this page is taken from the records below. Where two sources disagree, the disagreement is stated in the text rather than resolved silently.

  1. TMDBTMDB person record 6254111, Gu Do-hyung (Korean form of the name, romanisation variants, combined credits with character names and episode counts, external ids) themoviedb.org/person/6254111
  2. TMDBTMDB series record 323528, Backdoor (first and last air dates, episode count, status, network, production company, aggregate cast, keywords, premise) themoviedb.org/tv/323528
  3. TMDBTMDB series record 283300, Villains Everywhere (first and last air dates, episode count, network, cast) themoviedb.org/tv/283300
  4. TMDBTMDB series record 287344, The Practical Guide to Love (first and last air dates, episode count, network, production company, crew, cast, keywords) themoviedb.org/tv/287344

Wikipedia search, English and Korean editions: results covered unrelated Korean films and performers, so no biographical detail was taken from Wikipedia.

This product uses the TMDB API but is not endorsed or certified by TMDB.

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