Can I connect my non Apple TV to my Mac desktop?

If the TV is a flat-screen TV with HDMI inputs, there are two general means of doing it:

• HDMI connection from the Mac to the TV. This might require a USB-C to HDMI adapter or Mini DisplayPort to HDMI adapter, depending on the model of the Mac in question. If the TV is a UHD 4K TV, you'd want to check that the Mac supports 4K video output.
• AirPlay from the Mac to a "smart" TV (with AirPlay support) or compatible setup box (e.g., Apple TV box).

mrtn4852 wrote:

Can I connect my non Apple TV to my Mac desktop

Depends on the TV and Mac models. Different models/years Macs have different connectors. In general, as asked, yes you can connect a TV to your Mac.

We can not help you choose the correct connection without more detailed information.

What year model is your iMac?

see > Identify your iMac model - Apple Support

What is the make and model # of the TV?

(brand, size, model number, type of inputs or a web link to the spec's)

For the latest support article, see > Connect an external display to your iMac - Apple Support

Generally yes, however please note that you can use a TV as an external display for the Mac however you cannot use the Mac as an external display for the TV!!! In other words you cannot watch TV received on your TV on your Mac.