Even-denominator fractional quantum Hall states at half-filling are of particular interest because they can host non-Abelian quasiparticles. Here, we report the emergence of such states in the zeroth Landau level ($N=0$) of ABA trilayer graphene (TLG), challenging the conventional expectation that they are confined to the first excited Landau level. We observe robust incompressible states at $\nu =7/2$, $9/2$, and $5/2$ with their associated Levin-Halperin daughter states: $\nu =59/17$ and $46/13$ near $7/2$; $\nu =58/13$ and $77/17$ near $9/2$; and $\nu =43/17$ near $5/2$. These states appear exclusively within a finite displacement-field window coincident with crossings between symmetry-broken $N=0$ Landau levels carrying distinct isospin indices. The quantitative correspondence between the calculated crossing loci and the experimentally determined stability regions identifies Landau-level mixing as the microscopic origin. We attribute the stabilization of these even-denominator states to inversion-symmetry breaking in TLG, which enhances valley-resolved Landau-level hybridization and renormalizes short-range Coulomb interactions. Our results expand the landscape of even-denominator fractional quantum Hall states to multilayer graphene and establish TLG as a tunable platform for realizing non-Abelian anyons.

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• Edge states
• Electrical properties
• Fractional quantum Hall effect
• Landau levels
• Graphene