A compound, or a pharmaceutically acceptable salt thereof, represented by formula XXVI: wherein: X represents CH, C, -C(NH 2), or -C(NR a R b); -Y-R 4 represents -((C 1 -C 6)alkyl)-R 4, -CH 2 C -R 4, -CH 2 NH-R 4, -CH 2 N((C 1 -C 6)alkyl)-R 4, -CR a R b -R 4, -NH-R 4, -NHCH 2 -R 4, -NHC -R 4, -N((C 1 -C 6)alkyl)-R 4, -N((C 1 -C 6)alkyl)CH 2 -R 4, -N((CH 2) 2 OH)-R 4, -N[(C 3 -C 8)cycloalkyl(C 1 -C 6)alkyl]R 4, -heterocyclyl-R 4, -OR 4, -OCH 2 -R 4, -OC -R 4, -OC NR a R b, -SCH 2 R 4, or -SR 4, wherein the (C 1 -C 6)alkyl moiety of - ((C 1 -C 6)alkyl)-R 4 is optionally substituted; Z is absent or represents halo, hydroxy, (C 1 -C 6)alkyl, -CF 3, -OCF 3, (C 1 -C 6)alkoxy, aryl, aryloxy, amino, amino(C 1 -C 6)alkyl, -C NH 2, cyano, -NHC (C 1 -C 6)alkyl, -SO 2 (C 1 -C 6)alkyl, -SO 2 NH 2, or (C 3 -C 8)cycloalkyl; R 1c represents halo, amino(C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, cyano, -SO 2 CH 3, formyl, acyl, -NH 2, or optionally substituted aryl; R 2 represents halo, (C 1 -C 6)alkyl, (C 3 -C 8)cycloalkyl, (C 1 -C 6)fluoroalkyl, -OCH 3, - Si(CH 3) 3, -CONH 2, -C OH, cyano, or phenyl; R 3 represents -NH-, -O-, optionally substituted aryl, heteroaryl, carbocyclyl, or heterocyclyl; R 3a is absent or represents one or more substituents independently selected from the group consisting of halo, hydroxy, (C 1 -C 6)alkyl, -CF 3, -OCF 3, (C 1 -C 6)alkoxy, aryl, aryloxy, amino, amino(C 1 -C 6)alkyl, -C NH 2, cyano, -NHC (C 1 -C 6)alkyl, -SO 2 (C 1 -C 6)alkyl, and -SO 2 NH 2; and R 4 represents hydrogen, hydroxy, optionally substituted (C 1 -C 6)alkyl, optionally substituted (C 3 -C 8)cycloalkyl, heterocyclyl(C 1 -C 6)alkyl, (C 3 -C 8)cycloalkyl(C 1 -C 6)alkyl, -CH 2 OH, -CH((C 1 -C 6)alkyl)OH, - CH(NH 2)CH((C 1 -C 6)alkyl) 2, optionally substituted aryl, optionally substituted aryl(C 1 -C 6)alkyl, heteroaryl, optionally substituted heteroaryl(C 1 -C 6)alkyl, -CH 2 S(C 1 -C 6)alkyl, amino, or cyano; each R a and R b is independently H, (C 1 -C 8)alkyl, (C 2 -C 8)alkenyl, (C 2 -C 8)alkynyl, aryl(C 1 -C 8)alkyl, (C 3 -C 8)carbocyclyl, -C(=O)R c, -C(=O)OR c, -C(=O)NR c R d, -C(=O)SR c, -S R c, -S 2 R c, -S (OR c), or -SO 2 NR c R d; each R c and R d is independently H, (C 1 -C 8)alkyl, (C 2 -C 8)alkenyl, (C 2 -C 8)alkynyl, (C 4 -C 8) carbocyclyl, optionally substituted aryl, optionally substituted heteroaryl, -C(=O)(C 1 -C 8)alkyl, -S n (C 1 -C 8)alkyl, or aryl(C 1 -C 8)alkyl; or when R c and R d are bonded to a common nitrogen atom, then they may form a 3- to 7-membered heterocyclic ring; n is 2 or 3; and the stereochemical configuration at any chiral center is R, S, or a mixture of R and S. X represents CH, C, -C(NH 2), or -C(NR a R b); -Y-R 4 represents -((C 1 -C 6)alkyl)-R 4, -CH 2 C -R 4, -CH 2 NH-R 4, -CH 2 N((C 1 -C 6)alkyl)-R 4, -CR a R b -R 4, -NH-R 4, -NHCH 2 -R 4, -NHC -R 4, -N((C 1 -C 6)alkyl)-R 4, -N((C 1 -C 6)alkyl)CH 2 -R 4, -N((CH 2) 2 OH)-R 4, -N[(C 3 -C 8)cycloalkyl(C 1 -C 6)alkyl]R 4, -heterocyclyl-R 4, -OR 4, -OCH 2 -R 4, -OC -R 4, -OC NR a R b, -SCH 2 R 4, or -SR 4, wherein the (C 1 -C 6)alkyl moiety of - ((C 1 -C 6)alkyl)-R 4 is optionally substituted; Z is absent or represents halo, hydroxy, (C 1 -C 6)alkyl, -CF 3, -OCF 3, (C 1 -C 6)alkoxy, aryl, aryloxy, amino, amino(C 1 -C 6)alkyl, -C NH 2, cyano, -NHC (C 1 -C 6)alkyl, -SO 2 (C 1 -C 6)alkyl, -SO 2 NH 2, or (C 3 -C 8)cycloalkyl; R 1c represents halo, amino(C 1 -C 6)alkyl, (C 1 -C 6)alkoxy, cyano, -SO 2 CH 3, formyl, acyl, -NH 2, or optionally substituted aryl; R 2 represents halo, (C 1 -C 6)alkyl, (C 3 -C 8)cycloalkyl, (C 1 -C 6)fluoroalkyl, -OCH 3, - Si(CH 3) 3, -CONH 2, -C OH, cyano, or phenyl; R 3 represents -NH-, -O-, optionally substituted aryl, heteroaryl, carbocyclyl, or heterocyclyl; R 3a is absent or represents one or more substituents independently selected from the group consisting of halo, hydroxy, (C 1 -C 6)alkyl, -CF 3, -OCF 3, (C 1 -C 6)alkoxy, aryl, aryloxy, amino, amino(C 1 -C 6)alkyl, -C NH 2, cyano, -NHC (C 1 -C 6)alkyl, -SO 2 (C 1 -C 6)alkyl, and -SO 2 NH 2; and R 4 represents hydrogen, hydroxy, optionally substituted (C 1 -C 6)alkyl, optionally substituted (C 3 -C 8)cycloalkyl, heterocyclyl(C 1 -C 6)alkyl, (C 3 -C 8)cycloalkyl(C 1 -C 6)alkyl, -CH 2 OH, -CH((C 1 -C 6)alkyl)OH, - CH(NH 2)CH((C 1 -C 6)alkyl) 2, optionally substituted aryl, optionally substituted aryl(C 1 -C 6)alkyl, heteroaryl, optionally substituted heteroaryl(C 1 -C 6)alkyl, -CH 2 S(C 1 -C 6)alkyl, amino, or cyano; each R a and R b is independently H, (C 1 -C 8)alkyl, (C 2 -C 8)alkenyl, (C 2 -C 8)alkynyl, aryl(C 1 -C 8)alkyl, (C 3 -C 8)carbocyclyl, -C(=O)R c, -C(=O)OR c, -C(=O)NR c R d, -C(=O)SR c, -S R c, -S 2 R c, -S (OR c), or -SO 2 NR c R d; each R c and R d is independently H, (C 1 -C 8)alkyl, (C 2 -C 8)alkenyl, (C 2 -C 8)alkynyl, (C 4 -C 8) carbocyclyl, optionally substituted aryl, optionally substituted heteroaryl, -C(=O)(C 1 -C 8)alkyl, -S n (C 1 -C 8)alkyl, or aryl(C 1 -C 8)alkyl; or when R c and R d are bonded to a common nitrogen atom, then they may form a 3- to 7-membered heterocyclic ring; n is 2 or 3; and the stereochemical configuration at any chiral center is R, S, or a mixture of R and S.