And in the same vein, and the same trade, Jamie Heward. Both were injured at the time of the trade.
Andy Rogers was also acquired in the same trade, and never played with the Leafs, but at least played 1 game as a Marlie while under contract with the Leafs.
Chad Kilger- Florida Panthers
That was an interesting one too. The Panthers initially granted him leave, after the trade, but he failed to report after that allotted time.
He ended up becoming a firefighter back home, instead.
There are tonnes of LTIRetired examples, and we can get into things like draft prospects who refused to sign, without ever playing in the organization (a la Justin Schultz, or Eric Lindros), but more to the spirit of OP's question, one that stands out to me is Raffi Torres.
Traded to the Leafs in the Spaling/Polak trade, he wasn't even benched or training with the team, they just straight up told him to go home and not report to the club!
And more recently, never quite figured out what happened here... but Winnipeg acquired Alex Broadhurst from the Blue Jackets at last year's deadline, for future considerations. But they
immediately loaned him back to Columbus' farm team, where he already was. And then, (unless he snuck some in right at the end of the season), despite being on loan to the Monsters, he never played a game for them after the trade.
I guess it was just a matter of Jets wanting some depth players, in case of emergency, without disrupting their prospects playing time...