The Trillium Railway (reporting mark TRRY) is a Canadian short-line railroad operating in the province of Ontario.

In the Niagara Region, Trillium's trackage, referred to as Port Colborne Harbour Railway, is made up of Canadian National's former secondary and branch lines, including a number of urban spurs, on the west side of the Canal.

[1] Trillium no longer operates on the south tracks of the Townline Tunnel under the Welland Canal.

From July 2018 until the line's closure in December 2021, Trillium operated the Orangeville Brampton Railway under contract from the Town of Orangeville, taking over operations from Cando Rail Services Ltd.

[2] The St. Thomas and Eastern Railway operated over the former CN Cayuga Spur, the historical "Canada Air Line".