How to place a 7805 voltage regulator on a breadboard?

If you look carefully at the data sheet drawings, some have wider leads than others.

TI LM341/78M05

Fairchild LM78M05

A typical maximum diameter for a solderless breadboard is 0.91mm (AWG 19), so the Fairchild part will be too big, whereas the TI part will probably fit fine.

You could solder #22 or #24 wire to the 7805 leads, then poke those wires into thte breadboard.

Alternatively, build the voltage regulator on some perfboard (or just solder things together in mid-air), rather than trying to put the 7805 on the plastic breadboard.