Entanglement plays a role in the function and mechanical properties of proteins, yet few forms of entanglement have been identified so far and most require the terminals to be joined together probabilistically. We introduce a new method of detecting entanglement in proteins, by considering protein backbones together with all disulfide bridges and metal ions as \emph{spatial graphs} (i.e., conformations of graphs in $3$-dimensional space), without joining the terminals. These spatial graph proteins contain novel types of M\""{o}bius ladders, lassos, handcuff graphs, and knotted complete graphs on five vertices, which are more complex than previously known forms of entanglement in proteins. We illustrate each new type of entanglement as a subgraph of specific proteins that are deposited on the PDB.