拟卤素或类卤素（pseudohalogen）是一种性质类似卤素的无机化合物，其通式为 XY，其中 X 可以是氰基 CN、氰氧基 OCN、硫氰基 SCN 等官能基，而 Y 可以是上述的物质或是卤素原子。如氰气 (CN)₂、碘化氰 ICN 等都是拟卤素。拟卤素的特性是其官能基的反应类似卤素，而且官能基中的双键及三键不影响其化学特性。

奈米团簇（nanocluster）的铝（也被称为超原子）有时也被视为拟卤素，因为其化学性质和卤素离子类似，而且会形成 Al₁₃I₂（类似 I₃）及其他的化合物。这是由于小尺度下金属键的作用所造成。

The pseudohalogens are polyatomic analogues of halogens, whose chemistry, resembling that of the true halogens, allows them to substitute for halogens in several classes of chemical compounds. Pseudohalogens occur in pseudohalogen molecules, inorganic molecules of the general forms Ps–Ps or Ps–X (where Ps is a pseudohalogen group), such as cyanogen; pseudohalide anions, such as cyanide ion; inorganic acids, such as hydrogen cyanide; as ligands in coordination complexes, such as ferricyanide; and as functional groups in organic molecules, such as the nitrile group. Well-known pseudohalogen functional groups include cyanide, cyanate, thiocyanate, and azide.