Balrogs:

Maiar > Balrogs

Balrogs  by Eru-(Valar)
Balrog Numbers  by William Staples
More on Balrog Numbers  by Varda-(Valar)

Balrog of Moria/ Durin's Bane
Gothmog
Lungorthin

Images of Balrogs:

(more under individual Balrogs)
Image : Glorfindel and the balrog. Artist John Howe. Page: The Monastery of Ages