Henri Seppälä (born 7 June 1980), also known as Henkka T. Blacksmith, is the former bassist of the Finnish melodic death metal band Children of Bodom from 1995 to 2019.

When Samuli Miettinen quit Inearthed (the original name of Children of Bodom) in 1996, Seppälä joined the band, (asked by lead guitarist and singer, Alexi Laiho) he then adopted the 5-string bass.

He studied political history at the University of Helsinki when not on tour, and received his Master's Degree in 2012 with a thesis on the role of NGOs in rural development in Finland.

On the Children of Bodom official website, Seppälä lists his influences as Tom Araya, Billy Gould, Steve Brunner, Paulo Jr, Joe Principe and David Ellefson.

He boosts his sound with a Super Overdrive pedal or Tech21 Sansamp pre amp and uses an Audiotech Guitar Products Source Selector 1X6 Rack Mount Audio Switcher for switching between wireless units.