Yes, even when they are off they still consume electricity so unplug the cables when your not using them for a long period

Any TV made in the last 40 years uses electricity when off. This is to keep the circuits live. TVs before that took 30-45 seconds to get a picture (and when you turned them off, had a small dot that slowly faded away over a minute or two) until some enterprising inventor came up with the idea that got called "instant on."