Horst Sellentin (14 September 1922 – 10 May 1973) was a German baritone and a choral conductor.
Born in Berlin, Sellentin studied instrumental music, voice and conducting.
From 1948 he was a singer of the NDR Chor in Hamburg who also appeared as a soloist.
In 1960, he co-founded with Max Thurn the boys' choir of the NDR, called Knabenchor des Norddeutschen Rundfunks [de] in Hamburg and was its director.
When the choir became part of the new church St. Nikolai (Hamburg) [de], the name was changed to Hamburger Knabenchor St. Nikolai.