There are a number of surnames that commonly indicate Levite descent.
First, there are surnames that literally refer to Levite status. Such surnames include derivatives of the title HaLevy (meaning "the Levite"), including Levy, Levin, Levine, Levinson, Levitt, Lewi, Lewin, and Loewy.
Other surnames are derivatives of the title Segal (which is variously believed to be an acronym for "segan lekehunah," which means "second to the priest," "Segel Leviim," which means "Levite staff," or "Sgan Levi," which means "Levite deputy"), such as Segal, Segel, Sigal, Sigel, and the like. (The Segal surname is confusingly similar to Siegel, a surname spelled differently in Hebrew, which did not designate Levite descent. Because of this similarity, some Segal families became Siegels, and vice versa.) For more information about the derivation of Segal, click here.
Second, there are surnames that were used by well-known Levite families, such as the Horowitz rabbinical family.
Because (1) many Jews did not adopt surnames until the 19th century, (2) it was not uncommon for Jewish sons-in-law to adopt the surnames of illustrious fathers-in-law, and (3) surnames continued to be fluid into and after the 19th century, there are many Levites who do not have traditionally Levite surnames, and some non-Levites who have surnames that are traditionally Levite.
Yakov Yechezkel Halevi Lewin
b. 1897, Wyszkow, Poland, d. 1984, Haifa, Israel
Photo taken in @1917 in Wyszkow, Poland