SPR is an archive format used in Persona 3 and Persona 4. It contains TMX images, along with animation data.
Persona 3/4
SPR are sometimes found in PAC/BIN archives for bustups (because of the eye blinking frames) and HUD sprites (due to the rotation and resizing of HUD elements). Otherwise, SPRs contain groups of TMX images that are loaded together for a similar purpose, for instance, character icons.
Tools
Amicitia
Featured article: Amicitia (program)
Amicitia is TGE's all-in-one editor for Persona formats. It can be used to open SPR files and view, replace, or extract the TMX files inside. You can get it here.