The Greek Capital Letter Theta symbol (Ξ). Copy and paste it, or use its Unicode, HTML, and CSS codes.
More from Greek Letters.
The quickest way is to copy Ξ from this page and paste it anywhere. You can also insert it with its Unicode, HTML, or alt code listed above.
Ξ is U+0398 (decimal 920).
Use Θ in HTML to render Ξ on a web page.
On Windows you can type it with Alt+920 (hold Alt and enter the number on the numeric keypad).
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