GO Transit, VIA, CN, CP and the underground trains of the TTC's subway), and there are a few baby trains that are meant for fun rides such as those found at Centre Island (the Iron Horse in Centreville), Woodbine Mall (Fantasy Fair Express) and down at Roundhouse Park (Miniature Railway) across from the Rogers Centre.
Riding the Miniature Railway at Roundhouse Park
For those looking to find the full size trains you can check out the both Roundhouse Park (three pictures at top) and the Halton County Radial Railway collections.
Train tracks coming in from the north and west of Toronto into Union Station.
White and green of the GO Train.