Qenya
allane
pronoun. nobody, nothing (no thing), no one
alle
pronoun. nobody, nothing (no thing), no one
lálane Archaic
pronoun. nobody, nothing (no thing), no one
ni·kenne allane umma
I saw nobody at all
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
The correlative combinations ᴹQ. {aláqe, lāqe >>} alle, allane “nobody, nothing, no one” appeared Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/103 and note #41), pronominal forms of ᴹQ. alla “none”. There was also an archaic variant form †lálane and a more elaborate form ᴹQ. láqane “nobody, at all”. Drafts has laqe “nobody” in the phrase ᴹQ. tasse ni·kenne laqe imma “there I saw nobody whatsoever” (PE23/101-102 note #36).
Neo-Quenya: For purposes of Neo-Quenya I would use ᴺQ. alquen for “nobody, no one”, inspired by Q. ilquen “everbody”. Other neologisms for “nobody” include ᴺQ. alaquen from the NQW and ᴺQ. úquen from ABNW (ABNW) from the early 2000s. For “nothing” I would just use ᴹQ. alla.