Thorn with stroke
Ꝥ, or Þ with stroke was a scribal abbreviation common in the Middle Ages. It was used for Old English "þæt", as well as Old Norse "þor-", the "-þan"/"-ðan" in síðan, "þat", "þæt", and "þess". In Old English texts, the stroke tended to be more slanted, while in Old Norse texts it was straight. In Middle English times, the ascender of the þ was reduced, which caused the thorn with stroke abbreviation to be replaced with a thorn with a small t above the letter.
Unicode encodes Ꝥ as, and ꝥ at.
A thorn with a stroke on the descender also exists. The codepoints are, and.
