In terms of communication:
* Sender: This is the most common opposite of receiver in communication. The sender is the person or entity sending the message.
* Transmitter: Similar to sender, this refers to the device that transmits the message.
* Source: This is the origin of the message.
* Speaker: This is the person who is speaking in a conversation.
In terms of physical objects:
* Transmitter: This can refer to a device that sends signals.
* Emitter: This refers to something that sends out energy or particles.
* Source: This refers to the origin of something, such as a source of light or sound.
* Dispenser: This refers to something that gives out something, such as a dispenser of soap or water.
In terms of roles:
* Giver: This is the person giving something to another.
* Donor: This refers to someone who gives something freely.
* Provider: This is someone who supplies something to another.
Please provide more context about how you are using the word "receiver" so I can give you a more specific opposite.