Peter Todd, a contributor to bitcoin's open source code, has been very vocal about his opinions — and they aren't good for digital currencies.
Todd submitted his first bit of code to Bitcoin Core in April 2012, and today is #11 in terms of total commits to Core’s GitHub repo.
OP_CHECKLOCKTIMEVERIFY (BIP 65)
BIP 65 added “a new opcode (OP_CHECKLOCKTIMEVERIFY) for the Bitcoin scripting system that allows a transaction output to be made unspendable until some point in the future.”
In simpler terms, OP_CHECKLOCKTIMEVERIFY allows you to send money that cannot be spent until a specified future date.
Opt-in Full Replace-by-Fee Signaling (BIP 125)
BIP 125 explained opt-in full-RBF. Transaction fees are rising and opt-in full-RBF allows senders with stuck transactions to send a new transaction with a higher fee. Opt-in RBF was merged in Bitcoin Core version 0.12.
A BIP by Todd titled “Stealth Addresses” has been assigned BIP #63 but has yet to be published.