Ei Niš (Elektronska Industrija Niš) is a Serbian electronics manufacturer founded in 1948 in the city of Niš, in what was then Yugoslavia. The company grew into one of the largest electronics conglomerates in Southeastern Europe, producing a broad catalog of consumer and professional gear including radios, televisions, loudspeakers, telephones, semiconductors, and hi-fi audio equipment. Among musicians and audio enthusiasts it is best known for its vacuum tube production and for a line of integrated amplifiers and mixers sold under the Torero Hi-Fi name, including models such as the T16W and M40W.

The company's vacuum tubes earned a lasting reputation in the guitar amp and hi-fi worlds because Ei acquired original Telefunken tooling, enabling it to build tubes such as the ECC83 (12AX7), ECC81, ECC82, EL34, and EL84 using smooth-plate construction similar to the classic Telefunken designs. These tubes were widely adopted by amp builders and players through the 1980s and 1990s, and Ei-branded NOS stock remains sought after for its detailed, articulate character in both clean and overdriven applications.

EI Niš has 1 product cataloged on Equipboard, including Guitar Amplifier Tubes.