Lisu is a Unicode block containing characters of the Fraser Lisu alphabet for writing the Lisu language. The Fraser Lisu alphabet (and by extension the block) consists of glyphs resembling capital letters in the  basic Latin alphabet 0000–007F either in their standard form or turned upside down. (The addition of the block was subject to significant debate as to whether an entire block was necessary for the alphabet or if the turned letters not already in Unicode could instead be added under the Latin script section. Ultimately, the former approach was taken, and the Lisu letters are thus semantically different from their Latin counterparts.)

The Fraser alphabet or Old Lisu Alphabet is an artificial script invented around 1915 by Sara Ba Thaw, a Karen preacher from Myanmar, and improved by the missionary James O. Fraser, to write the Lisu language. It is a single-case (unicameral) alphabet.

The alphabet uses uppercase letters from the  Latin script 0000–007F , and rotated versions thereof, to write consonants and vowels. Tones and nasalization are written with Roman punctuation marks, identical to those found on a typewriter. Like the Indic abugidas, the vowel is not written. However, unlike those scripts, the other vowels are written with full letters.

The Chinese government recognized the alphabet in 1992 as the official script for writing in Lisu.