We report for the first time the antiviral activities of two <i>iminovirs</i> (antiviral imino-<i>C</i>-nucleosides) <b>1</b> and <b>2</b>, structurally related to galidesivir (Immucillin A, BCX4430). An <i>iminovir</i> containing the 4-aminopyrrolo[2,1-<i>f</i>][1,2,4-triazine] nucleobase found in remdesivir exhibited submicromolar inhibition of multiple strains of influenza A and B viruses, as well as members of the <i>Bunyavirales</i> order. We also report the first syntheses of ProTide prodrugs of <i>iminovir</i> monophosphates, which unexpectedly displayed poorer viral inhibition than their parent nucleosides <i>in vitro</i>. An efficient synthesis of the 4-aminopyrrolo[2,1-<i>f</i>][1,2,4-triazine]-containing <i>iminovir</i> <b>2</b> was developed to enable preliminary <i>in vivo</i> studies, wherein it displayed significant toxicity in BALB/c mice and limited protection against influenza. Further modification of this anti-influenza <i>iminovir</i> will therefore be required to improve its therapeutic value.